[21] GUIDED GROWTH OF CDS NANOWALLS WITH CONTROLLED ORIENTATIONS FOR HIGH-PERFORMANCE NANO-MISFET AND PHOTODETECTOR ARRAYS

 

Jinyou Xu1, Ernesto Joselevich1

1 Department of Materials and Interfaces; Weizmann Institute of Science

Guided Growth of CdS Nanowalls with Controlled Orientations for High-Performance nano-MISFET and Photodetector Arrays.
Jinyou Xu†, Ronit Popovitz-Biro‡, Katya Rechav‡, Lothar Houben‡, Ernesto Joselevich*†.
†Department of Materials and Interfaces, ‡Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel

Controlled alignment of semiconductor nanostructures plays key roles for large-scale integration of them into functional nanodevices. Here we report the horizontally guided growth of CdS nanowalls with controlled crystallo-graphic orientations on both flat and faceted sapphires by a simple thermal evaporation route. HRTEM, GPA and micro-PL analyses confirmed the high single-crystal quality of these nanowalls. On the basis of these horizontally self-aligned nanowalls arrays, nano-MISFETs and photodetectors arrays were conveniently fabricated in a wafer scale (cm2) and high-performances were achieved. Most of the nano-MISFETs work in a E-mode (normally off) with on/off current ratio of 108 and a highest transconductance of 1.1 µS. The on/off ratio is four orders of magnitude higher than the best reported results for E-mode CdS nano-FETs. The best rise and decay time of the photodetectors is ~1 µs and the 3-dB bandwidth is ~350 kHz, which is one order of magnitude faster than the best results reported so far. Therefore, the present route holds promising to develop large-scale fabrication of high-performance semiconductor nanodevices.

 

[25] ULTRA HIGH-YIELD SYNTHESIS OF SELF-ASSEMBLED, CONDUCTIVE, AND SUPERHYDROPHOBIC THREE-DIMENSIONAL MATS OF CARBON NANOFIBERS VIA FULL CATALYSIS OF UNCONSTRAINED THIN FILM

 

Efrat Shawat Avraham1, Ilana Perelshtein1, Andrew westover2, Cary L. pint2, Daniel Nessim3

1 Bar-Ilan University; Bar-Ilan University
2 Vanderbilt University, Nashville, Tn ; Vanderbilt University, Nashville, Tn
3 Bar-Ilan Institute of Nanotechnology and Advanced Materials; Bar-Ilan University

Ultra high-yield synthesis of self-assembled, conductive, and superhydrophobic three-dimensional mats of carbon nanofibers via full catalysis of unconstrained thin film
Efrat Shawat1, Ilana Perelshtein1, Andrew Westover2, Cary L. Pint2, and Gilbert D. Nessim1*

Abstract:
Carbon nanofibers (CNFs) are ideal candidates for a range of important applications; However, to realize industrial application of these materials, processes must be developed to produce CNfs with desired structural characteristics, and with high yields.
Using a specific weak adhesion layer between the CNf catalyst and the substrate, we produced a catalytic thin film that delaminates inside our CVD reactor during synthesis. Following delamination, removal of the mechanical constraint of the catalyst layer to the substrate led to mats of carbon nanofibers that were 3X to 5X larger than the substrate they originated from. The mass of these three-dimensional (3-D) CNF mats made of cm-long Following an extensive characterization of the morphology and structure of the CNF mats in concert with a parametric study of the effect of temperature, pre-anneal conditions, growth duration, and substrate materials, we found evidence of a correlation between growth conditions and the 3-D mat morphological properties. This work gives insight into a new growth process whereby high yields of 3-D carbon nanostructures can be directly obtained with from an unconstrained catalytic thin film, utilizing a rational choice of catalyst/underlayer combinations and growth conditions. This yield is over an order of magnitude higher compared to the “standard” substrate-constrained catalytic growth. Based on the extensive characterizations done to date, we can explain specific aspects of the new growth mechanisms based on thin film evolution, simultaneous delamination, and carbon nucleation of the catalytic thin film. Such materials have significant promise as conductive material scaffolds for a wide-range of next-generation materials that can take advantage of the high surface area and good mechanical robustness of such CNF structures.

 

[26] CATALYST RESERVOIR FOR SYNTHESIS OF TALLER CARPETS OF CRYSTALLINE AND VERTICALLY ALIGNED CARBON NANOTUBES

 

Efrat Shawat Avraham1

1 Bar-Ilan University; Bar-Ilan University

Catalyst reservoir for synthesis of taller carpets of crystalline and vertically aligned carbon nanotubes
Efrat Shawat, Dr. Yafit Fleger, Dr. Cary L. Pint , Dr. Gilbert Daniel Nessim
The Department of Chemistry and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan , 52900, Israel

Abstract:
Overcoming growth termination remains a challenge for the synthesis of long CNTs. As it has been proposed that the termination of growth is correlated with catalyst morphology evolution and subsurface diffusion of catalyst, we propose here the design of a catalyst stack composed of a thin oxide support under which resides a catalyst reservoir to replenish the catalyst during CNT synthesis, and hence enhance the lifetime and activity of the catalyst. Specifically, we compared samples with e-beam evaporated Fe thin film catalyst on Al2O3 underlayer and samples with an additional thin Fe reservoir beneath the alumina underlayer. With the inclusion of the Fe sublayer, we synthesized CNT carpets that were up to 100% taller compared to those samples without the Fe sublayer. The effectiveness of the Fe sublayer was observed for wide variations of process parameters such as growth duration and temperature. High-resolution imaging confirms the presence of carpets composed of crystalline and vertically aligned CNTs with lengths up to almost 2mm.AFM carried out on samples using comparable process conditions showed a bimodal formation of Fe catalysts for the samples with the Fe sublayer, and subsequent etching experiments emphasize the presence of pinholes in the alumina support which enables the redistribution of Fe catalyst from the sublayer to the overlayer. A study of samples with varying thicknesses of the alumina underlayer further confirmed this hypothesis as thicker alumina layers exhibited shorter CNT growth due to the presence of fewer pinholes. This result is significant as it elucidates further mechanistic aspects of CNT growth and provides a new technique to extend the active lifetime of CNT growth catalyst, and thus enhance the CNT length.

 

[31] 3X TALLER CARPETS OF VERTICALLY ALIGNED CARBON NANOTUBES THROUGH DIFFERENTIAL PREHEATING OF HYDROCARBON DECOMPOSITION AND WATER FORMATION

 

Eti Teblum1, Reut Yemini1, Mijael Chababo1, Efrat Shawat Avraham1, Merav Muallem2, Daniel Nessim2

1 Bar-Ilan University; Bar-Ilan University
2 Bar-Ilan Institute of Nanotechnology and Advanced Materials; Bar-Ilan University

It has been shown that preheating the incoming hydrocarbon precursors and of forming water vapor from oxygen and hydrogen can significantly affect the growth of vertically aligned carpets of carbon nanotubes (CNTs). In this study, we performed differential preheating of the incoming gases to decouple the water formation and the hydrocarbon decomposition processes. We identified different process parameter sweet spots for water vapor formation (formed by reacting H2 and O2) and for hydrocarbon decomposition as well as significantly increasing the height of our CNT carpets. Specifically, we revealed that the optimal preheating temperature for hydrocarbon formation is quite lower compared to the optimal preheating temperature required water decomposition.
We used a sophisticated system of multi-zone thermal chemical vapor deposition (CVD) furnaces in parallel and in series to study the effects of thermal preheating of these precursors prior to their reaching the growth zone. We analyzed a dozen of possible preheating combinations and showed how an appropriate combination of gas residence times for both hydrocarbons and water formation can significantly increase CNT growth to exceed 3 mm in height. Extensive AFM, HRTEM and SEM characterizations of the CNTs indicate how preheating affects the CNT height, diameter, and crystallinity. This analysis helps to better understand the mechanisms at play for the precursor gases prior to reaching the sample and helps to design more efficient synthesis systems for CNT growth. Moreover, this insight may open the door to the development of more sophisticated thermal CVD system where different incoming precursors are heating differently to optimize the growth of CNTs and possibly of other nanostuctures.

 

[39] ENGINEERING OF IRON-BASED MAGNETIC NANOPARTICLES FOR ENVIRONMENTAL REMEDIATION APPLICATIONS

 

Hai Haham1, shlomo Margel2

1 Department of Chemistry; The Institute of Nanotechnology and Advanced Materials
2 Biu; Department of Chemistry & The Institute of Nanotechnology and Advanced Materials

Engineering of Iron-Based Magnetic Nanoparticles for Environmental Remediation Applications
Hai Haham and Shlomo Margel

Magnetic nanoparticles represent a new generation of environmental remediation technologies that could provide cost-effective solutions to some of the most challenging environmental contamination problems. This study presents two methods for engineering iron-containing water treatment utilities based on: (a) magnetic nanoparticles; (b) magnetic carbon fabrics. Magnetic Fe nanoparticles coated with carbon layers were obtained by thermal decomposition of ferrocene mixed with polyvinylprrolydone (PVP) at 350 ˚C, followed by thermal annealing at 600 ˚C in inert atmosphere. Magnetic activated carbon fabrics (ACF) were produced by thermal decomposition of iron acetylacetanoate impregnated within the ACF at different temperatures in inert atmosphere. The influence of the annealing temperature on the chemical composition, shape, crystallinity, surface area, pore volume and magnetic properties was elucidated for both cases. The Fe nanoparticles obtained in these two methods were doped with tinier Pd nanoparticles for catalysis applications. The engineered utilities were tested on two classes of pollutants (haloganted and azo dyes) and illustrated the enhanced decomposition of the dyes from an aqueous solution according to the following order: Fe/Pd > Fe > Fe3O4.

 

[43] SUBSTRATE STRAIN, IT’S DETERIORATING EFFECT ON THE TRANSPORT PROPERTIES OF THE VO2 METAL-INSULATOR TRANSITION AND HOW TO OVERCOME IT

 

Tony Yamin1, Amos Sharoni2

1 Biu; Bar-Ilan Institute of Nanotechnology & Advanced Materials
2 Biu; Department of Physics & The Institute of Nanotechnology and Advanced Materials

Substrate strain, it’s deteriorating effect on the transport properties of the VO2 metal-insulator transition and how to overcome it

When growing functional oxide thin films the substrate matching and induced strain play crucial roles on the resulting film’s electronic and structural properties. In VO2 this often results in a minimum deposition thickness necessary for the appearance of the metal insulator transition (MIT), where increasing thickness further changes the properties of the transition until full relaxation.
We developed a delicate wet etching process for thinning epitaxial films of VO2 grown on R-cut sapphire, which can open a new path for fabrication of ultra-thin devices based on VO2.
Our initial 60 nm thick film showed a sharp MIT of ~ 4 orders of magnitude. The film was etched, in a number of steps, to below 10 nm. We find that the transport properties of the etched film did not change substantially till the film was thinned below 15 nm, and also film below 10 nm showed MIT. This is in contradiction to films that were deposited to 20nm or below and had no phase transition. We report the transport, XRD and TEM properties of the thinned films and the films deposited at different thickness, and discuss the correlation between structure and transport properties, and the different routes to control the substrate strain.

 

[51] CITRAL ENCAPSULATION TO CHITOSAN-BASED EDIBLE FILMS AND COATINGS UTILIZING NANO-EMULSION APPROACH

 

Hadar Arnon1, Elena Poverenov2, Ron Porat2

1 Agriculture Research Organization (Aro); Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem
2 Agricultural Research Organzation (Aro); Postharvest and Food Sciences, Food Quality and Safety

Citral encapsulation to chitosan-based edible films and coatings utilizing
nano-emulsion approach
Active edible coatings may provide a natural safe and biodegradable alternative to synthetic preserving agent for prolonging shelf life of fruits and vegetables. In this study citral, a natural aroma and antimicrobial agent, was encapsulated to a chitosan-based coating formulation utilizing nano-emulsion approach. The properties and functionality of the nano-emulsions containing formulation were compared to those of the conventional coarse emulsions containing formulations. DLS analysis showed that nano-emulsion had higher monodispersity than the coarse emulsion. The surface structure, seen from E-SEM studies was found to be more organized in edible films based on nano-emulsions. Encapsulation of citral generally impaired the mechanical properties of the films; however the negative effect of nano-emulsions is significantly smaller than that of the coarse emulsions. Moreover, nano-emulsions even increased the ‘elongation at break’ value. The water vapor permeability (WVP) of chitosan edible films was not significantly impaired by citral encapsulation. The effect of the active edible coatings was examined on fresh-cut melons model. The nano-emulsions based coatings demonstrated advanced performance. The antimicrobial effect of the coatings was studied utilizing different concentrations of citral (0.8, 1.6, 2.4 % v/v). It was found that 1.6% (v/v) and especially 2.4% (v/v) citral significantly inhibited the microbial growth during all examination period (13 days).

 

[53] FABRICITION OF N-HALAMINE NANOPARTICLES FOR ANTIMICROBIAL AND ANTIFOULING APPLICATIONS

 

Michal Natan1, Ori Gutman1, Shlomo Margel1, Ehud Banin2

1 The Institute for Advanced Materials and Nanotechnology; Bar Ilan University
2 The Mina and Everard Goodman Faculty of Life Sciences; The Institute for Advanced Materials and Nanotechnology

Increased resistance of bacteria to antimicrobials and their ability to form biofilms, many of them are essentially untreatable, pose a serious public health threat worldwide. This has prompted the search for agents that can inhibit both bacterial growth and withstand harsh conditions (e.g., high organic loads). In the current study, N-halamine-derivatized cross-linked polymethacrylamide nanoparticles (NPs) were synthesized by co-polymerization of the monomer methacrylamide (MAA) and the cross-linker monomer N,N-methylenebisacrylamide (MBAA), and were subsequently loaded with oxidative chlorine, using sodium hypochlorite (NaOCl). The chlorinated NPs demonstrated remarkable stability and durability to organic reagents and to repetitive bacterial loading cycles as compared with the common disinfectant NaOCl (bleach), which was extremely labile under these conditions. The antibacterial mechanism of the cross-linked P(MAA-MBAA)-Cl NPs was found to involve generation of reactive oxygen species (ROS) only upon exposure to organic media. Importantly, ROS were not generated upon suspension in water, revealing that the mode of action is target-specific. Further, a unique and specific interaction of the chlorinated NPs with Staphylococcus aureus was discovered, whereby these microorganisms were all specifically targeted and marked for destruction. This bacterial encircling was achieved without using a targeting module (e.g., an antibody or a ligand) and represents a highly beneficial, natural property of the P(MAA-MBAA)-Cl nano-structures. Finally, P(MAA-MBAA)-Cl NPs embedded within irrigation drippers were shown to prevent fouling on them compared with the control, hence providing the drippers with ‘self-cleaning’ and ‘self-sterilizing’ properties. In summary, our findings underscore the potential of developing sustainable P(MAA-MBAA)-Cl NPs-based devices for inhibiting bacterial colonization and growth.

 

[60] SIZE DEPENDENT LIGAND LAYER DYNAMICS IN SEMICONDUCTOR NANOCRYSTALS PROBED BY ANISOTROPY MEASUREMENTS

 

Ido Hadar1, Tasfrir Abir1, Shira Halivni2, Adam Faust3, Uri Banin4

1 Institute of Chemistry and the Center for Nanoscience and Nanotechnology; The Hebrew University of Jerusalem
2 Hebrew University of Jerusale; Physical Chemistry
3 Institute of Chemistry and the Center for Nanoscience and Nanotechnology ; The Hebrew University of Jerusalem
4 Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem ; The Hebrew University of Jerusalem

Colloidal semiconductor nanocrystals (NCs) are promising building blocks for various applications. This is mainly due to the ability to modify the physical and chemical properties of the semiconductor material via bottom-up approaches by controlling the particles size and shape in the nanometer scale. The inorganic NC surface is usually covered by an organic ligands layer, making NCs a unique inorganic-organic hybrid chemical system. The ligand shell has a crucial role in the colloidal synthesis as it allows controlling the size and shape of the NCs. Modifying the properties of the ligand shell allows controlling the NCs dispersibility in various solvents and matrices to control their physical and chemical properties and to adapt them for specific applications. Although the major importance of the ligand shell its exact properties and specifically the effect of the NC size and shape on these properties are still not well understood. This is mainly due to the lack of experimental tools that will enable to study the organic ligands shell in situ. In our current research we have uniquely studied the physical properties of the ligand shell on the surface of spherical quantum-dots (QDs), of various sizes. We have utilized organic dye molecules that are embedded within the ligands layer and adopt its properties to optically study the effective viscosity of the ligand shell. By tracing the reorientation times of the dye molecules we were able to calculate the effective viscosity of the ligand layer. We have found that as the size of the QD decreases (and hence the curvature increases), the effective viscosity of the ligands shell is decreasing. The ability to control the physical properties of the ligand shell simply by changing the shape of the surface is a unique property of NCs. Further investigation of the ligand shell will allow rational design of the surface to achieve desired properties, providing an additional important knob for tuning their functionality.

 

[61] SYNTHESIS AND CHARACTERIZATION OF SPIROPYRAN PHOTOCHROMIC FLUORESCENT POLYMERIC NANOPARTICLES BY EMULSION POLYMERIZATION

 

Sharon Bretler1, Uriel Bretler2, shlomo Margel3

1 Department of Chemistry; The Institute of Nanotechnology and Advanced Materials
2 Bar Ilan Institute of Nanotechnology and Advanced Materials; The Institute of Nanotechnology and Advanced Materials
3 Biu; Department of Chemistry & The Institute of Nanotechnology and Advanced Materials

Abstract:
Photochromic fluorescent nanoparticles were prepared by emulsion polymerization of styrene (S), butylmethacrylate (BMA), and monomer spiropyran dye (MSP) to obtain Poly(S/BMA/MSP) uniform nanoparticles.
The influence of various polymerization parameters (e.g., concentration of the monomers, initiator, and the surfactant) on the properties of the particles size, and size distribution has been elucidated.
Spiropyran is colorless and non-fluorescent at the spiro conformation. Moreover, spiropyran at the merocyanine conformation is non-fluorescent in water or in non-polar organic solvents. Once the merocyanine conformation spiropyran is entrapped within polymer particles, the particles exhibit blue color and strong red fluorescence.
Absorbance and fluorescence measurements reveal that higher BMA concentration at the polymerization reaction leads to a higher absorbance and fluorescence intensity of the Poly(S/BMA/MSP) nanoparticles.
The photoisomerization of the Poly(S/BMA/MSP) nanoparticles studied by exposing the nanoparticles dispersion to alternate UV and visible light cycles, the fluorescence intensity measurements reveal a reversible photochromism.

 

[65] CONTROLLING FORMATION OF NANOSTRUCTURES AND MICROSTRUCTURES WITH ACOUSTIC WAVES

 

Haim Sazan1, Michael Layani2, Silvia Piperno3, Shlomo Magdassi4, Hagay Shpaisman5

1 Bar-Ilan University; Nano Technology Institute
2 Casali Institute for Applied Chemistry; Institute of Chemistry
3 Chemistry Department.; Bar Ilan University
4 Casali Center of Applied Chemistry; The Hebrew University of Jerusalem
5 Bar Ilan University; Nanotechnology Institute

Abstract – Controlling Formation of Nanostructures and Microstructures with Acoustic Waves

Haim Sazan1, Michael Layani2, Silvia Piperno1, Shlomo Magdassi2, Hagay Shpaisman1
1The Nanotechnology Institute, Chemistry Department, Bar-Ilan University, Ramat-Gan, Israel
2Casali Institute for Applied Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

In this research, I study how standing surface acoustic waves (SSAWs) affect the formation of structures from suspended nanoparticle solutions and control chemical reactions. Recently, SSAWs were used to selectively promote coalescence and to create ordered colloidal crystals and metamaterials. SSAWs could be used to create new microstructures – metallic, polymeric and hybrid (organic-inorganic) materials and to control surface reactions. Under the exposure of SSAWs, nanoparticles in a microfluidic channel would be forced towards pressure nodes (for particles with a positive acoustic contrast factor in the medium). If the acoustic force pushing them together is stronger than the electrostatic forces arising from their charges, coalescence and partial fusion could occur. When the system partly fuses, we predict that microstructures will be formed following the contour of the nodes.
I investigate the formation of microstructures by silver nanoparticles sintering. These nanoparticles can be sintered at room temperature with exposure to chloride ions. Streaming the silver suspended nanoparticles with chloride ions solution under the SSAWs field could sinter the particles in a micro-fiber shape.
Another project is controlling chemical reaction, such as crystallization growth of titanium oxide, by SSAWs exposure. As opposed to the silver nanoparticles sintering where the nanoparticles are being arranged instantly by the acoustic waves and then the stabilizer is removed to form nano/microstructures, here crystals grow along the pressure nodes lines.

Illustration (not to scale) of pattern formation due to the effect of SSAW on particles inside a microfluidic channel

 

[83] VISCOELASTIC PROPERTIES OF FROZEN INTERFACIAL NANO-LAYERS: DIRECT OPTICAL MICROSCOPY

 

Moshe Caspi1, Alexander V. Butenko1, Eli Sloutskin1

1 Physics Department and Bar-Ilan Institute for Nanotechnology and Advanced Materials, Bar-Ilan University; Institute for Nanotechnology and Advanced Materials

Viscoelastic properties of frozen interfacial nano-layers:
Direct optical microscopy
M. Caspi, A. V. Butenko, and E. Sloutskin
Physics Department and Institute of Nanotechnology and Advanced Materials,
Bar-Ilan University, Ramat-Gan 5290002, Israel
The classical theory of elasticity is a continuum approximation. In nano-scale systems, where the relevant length scale approaches the dimensions of atoms and molecules, this continuum approximation is doomed to fail. However, even the most fundamental concepts of nanoelasticity, beyond the limits of the continuum approximation, are yet not established.
We employ passive microrheology to study the viscoelastic properties of a quasi-two-dimensional crystalline nano-layer, which spontaneously self-assembles at the interface between oil and water. The properties of oil-water interfaces play a dominant role in a wide range of systems in science and technology. It has been recently discovered[L. Tamam et al. PNAS (2011)], that tiny concentrations of certain surfactants make the interface between oil and water undergo a freezing transition at T=Ts. At a high temperature (T>Ts), the ~2nm thick monomolecular interfacial layer, composed of a mixture of oil (linear alkane) molecules and surfactants, is molten. At a lower temperature (T<Ts), the monolayer crystallizes, about 10-20oC above the freezing temperature of the bulk oil. The elastic properties of this crystalline interfacial monolayer play a dramatic role for oil in water droplets: the droplets, down to sub-femtolitre sizes, become faceted and, under certain conditions, mix spontaneously with water, overcoming the hydrophobic repulsion[S. Guttman et al. PNAS (under revision, 2015)]. Yet the viscoelasticity of the interfacially-frozen monolayers has never been measured before.
We follow, by direct confocal microscopy, the Brownian motion of simple colloidal spheres, embedded in a monolayer between bulk hexadecane (C16-alkane) and an aqueous sub-mM solution of linear ionic surfactants (C18TAB). The viscoelastic properties of the interfacial monolayer are probed for a range of different temperatures, both below and above Ts, potentially allowing the future paradigm of nanoscale elasticity to be established based on direct experiments.

 

[90] SONOCHEMICAL SYNTHESIS OF ZNO-PVA NANOFLUID AS POTENTIAL BIOCIDAL AGENT

 

Anjani Nagvenkar1

1 Bar- Ilan University, ; Institute for Nanotechnology and Advanced Materials

Sonochemical synthesis of ZnO-PVA nanofluid as a potential biocidal agent
Anjani Nagvenkar, † Archana Deokar, † Ilana Perelshtein, † Aharon Gedanken†§
†Department of Chemistry, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
§Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Abstract
The study aimed at synthesizing ZnO in colloidal form with greater stability and higher antibacterial activity. From practical application point of view, for the incorporation of ZnO into liquid products the use of a stabilizer becomes necessary but synthesizing nanoparticles with high dispersity in solution still remains a challenge. So herein we attempt the synthesis of ZnO in colloidal form by employing a biocompatible polymer, PVA (poly(vinyl alcohol)) as a stabilizing agent to achieve stability on the one hand and minimum particle size of ZnO on the other hand. Both ZnO (without PVA) and ZnO-PVA are synthesized using ultrasonic irradiation and the difference in their particle size, stability and antibacterial activity was correlated. Furthermore, ESR measurements reveal that ZnO with reduced particle size produced increased levels of reactive-oxygen species (ROS). The biocidal effect of the colloidal solution was performed on two bacterial species: Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) revealed an enhancement in the antibacterial activity for the ZnO-PVA nanofluid.

 

[98] CONTROLLING WIRE FORMATIONS WITH LASER INDUCED MICROBUBBLES

 

Nina Armon1, Hagay Shpaisman2, Michael Layani3, Shlomo Magdassi4, Udi Greenberg2

1 Bar Ilan University; Nanotechnology Institure
2 Bar Ilan University; Nanotechnology Institute
3 Casali Institute for Applied Chemistry; Institute of Chemistry
4 Casali Center of Applied Chemistry; The Hebrew University of Jerusalem

Controlling wire formations with laser induced microbubbles
Nina Armon1, Michael Layani2, Udi Greenberg1, Shlomo Magdassi2, Hagay Shpaisman1
1The Nanotechnology Institute, Chemistry Department, Bar-Ilan University, Ramat-Gan, Israel
2Casali Institute for Applied Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
In my research I focus on directing nano-particles to form microstructures by induced laser light. My sample is composed of an aqueous solution of the micro/nano particles that are dispersed between two glass slides. As the focused laser beam heats the micro/nano particles solution vapor pressure rises and can result in the formation of a microbubble. This causes a temperature gradient in the vicinity of the bubble that gives rise to strong Gibbs−Marangoni convection currents. As a result of the flow, the micro/nano particles are pushed towards the edge of the bubble/glass contact area and can be pinned there. Moving the focused beam relative to the sample results in the migration of the microbubble, thus continuously depositing fresh material at the bubble/glass contact area.
Since previous work has shown fragmented lines, our goal was to learn how to get better control over the microbubble in order to produce continuous lines with minimum width. As a model system we used solutions of Ag nano particles with a polyacrylic acid coating in different solvents. We have found that modulating (altering the frequency and duty cycle) the exposure time of the laser beam can significantly improve the quality of the forming lines. Additionally, we found a strong dependence on the boiling point of the solvent, intensity of the laser, microscope’s stage velocity, microscope’s magnification and material concentration in the solution.

 

[99] EFFECT OF OVERLAYERS ON THE GROWTH OF CARBON NANOTUBE FOREST

 

Reut Yemini1, Daniel Nessim2

1 Bar-Ilan University; Bar-Ilan University
2 Bar-Ilan Institute of Nanotechnology and Advanced Materials; Bar-Ilan University

Effect of overlayers on the growth of carbon nanotube forest
Reur Yemini and Gilbert D. Nessim

Since the discovery of carbon nanotubes and the fundamental understanding of their growth mechanism, most researchers focused on the influence of different growth parameters and variety of substrates on vertically aligned carbon nanotubes (VACNTs) growth. Most research has focused on understanding the role of catalysts, underlayers, gases, and most recently thin film reservoirs position below the alumina underlayer. In this study, we demonstrate the effect of different metallic bridges positioned above the catalytic layer on the growth of VACNTs using thermal chemical vapor deposition (CVD). We show that the growth of CNTs can be enhanced or inhibited by using different materials. Using patterned metal foils or wires we were able to pattern regions with CNTs of varying height with regions without CNTs. For instance, we show how copper inhibited CNT growth while titanium bridges led to taller CNTs beneath. Using HRTEM and HRSEM we will show the effect of these metallic bridges on the catalyst morphology and on the CNT structure. We will discuss mechanisms of how the bridges affect the precursor gases in proximity of the catalytic layer. This research shows how we can control CNT growth on different regions of the same sample, without the need to pattern the catalyst.

 

 

 

 

[110] PLATINUM FREE CATALYSTS FOR HYDROGEN OXIDATION REACTION (HOR) IN ALKALINE FUEL CELLS

 

Masha Alesker1

1 Bar Ilan University; Bina Institute

Platinum Free catalysts for Hydrogen Oxidation Reaction (HOR) in Alkaline Fuel Cells
Maria Alesker, Meital Shviro, David Zitoun

Department of Chemistry, Nanomaterials Research Center, Bar Ilan Institute of Technology and Advanced Materials (BINA), Bar Ilan University, Ramat-Gan, 52900, Israel

Investigation of the hydrogen oxidation reaction (HOR) in alkaline media has been pursued in the past few years side by side with the development of alkaline membrane fuel cells (AMFCs), also called anion exchange membrane fuel cells (AEM-FCs). We present the synthesis, electrochemistry and AMFC test of a platinum-free HOR catalyst. The anode catalyst is prepared by the synthesis of a tri-component nano-composite of carbon, palladium and an oxophilic metal (nickel), resulting in nano-dispersed, interconnected crystalline phases of Ni and Pd. When used in the anode of a hydrogen/air AMFC, such Pd/Ni catalyst exhibits high HOR activity, resulting in record high performance for a platinum-free AMFC. The enhancement of HOR catalytic activity vs. that observed at Pd (or Ni) alone is revealed directly in rotating disc electrode tests of this Pd/Ni catalyst that shows a significant negative shift (200 mV) of the onset potential for the HOR current vs. the case of Pd.

 

[114] IN SITU FORMATION OF CARBON DOTS AIDS AMPICILLIN SENSING

 

Rahul Mishra1, Indra Neel Pulidindi1, Eihab Kabha1, Aharon Gedanken2

1 Bar Ilan University; Department of Chemistry
2 Bar-Ilan University; Department of Chemistry

In situ formation of carbon dots aids ampicillin sensing
Rahul Kumar Mishraa, Indra Neel Pulidindia, Eihab Kabhaa, Aharon Gedankena, b*
aDepartment of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel
bNational Cheng Kung University, Department of Materials Science and Engineering, Tainan 70101, Taiwan
Tel: +972-3-5318315; Fax: +972-3-7384053;
*E-mail: [email protected]
Abstract:
A simple analytical method is designed for the detection of micro molar concentrations of antibiotics with β- lactam subunit. The sensor for the ampicillin has a limit of detection, LOD value of 0.165 x 10-4 M and exhibited linearity over a wide range of ampicillin concentration 6.6 – 200 ppm. The detection of antibiotic is based on the in situ generation of carbon nano dots (CND’s) via a hydrothermal reaction between glucose and the antibiotic moiety. The CND’s exhibited characteristic absorption at 340 nm whose intensity is a measure of the initial ampicillin concentration. The CND’s possess peculiar blue emission which is excitation dependent. The particle size of CND’s is in the range of 8-40 nm (Fig. 1) and are hydrophilic. NMR spectral analysis revealed insights into the carbon nano structure comprising of aromatic core with carbonyl type functionalities on the surface.

Fig. 1 . TEM image of carbon dots aided the sensing of ampicillin

 

[120] A NOVEL METHOD OF FUNCTIONALIZATION OF INORGANIC TUNGSTEN DISULFIDE NANOTUBES

 

Daniel Raichman1

1 Bar-Ilan University; Chemistry Department

A novel method of functionalization of inorganic tungsten disulfide nanotubes
Daniel Raichman, Rina B. Binyamini and Jean Paul Lellouche
Bar-Ilan Institute of Nanotechnology & Advanced Materials
The covalent attachment of functional ligands such as photo or redox active molecular species onto the surface of inorganic WS2 nanotubes is an important first step towards the design of new mechanically hard materials/matrices. Such successful applications, however, will strongly fuel surface chemical modifications for best contacting phase compatibility.A new method of functionalization/polycarboxylation on the surface of WS2 inorganic nanotubes was successfully developed using electrophilic species (Scheme below). This main functionalization trend was to enable a wide range of INT surface modifications via polyCOOH group chemical activation such as outer polyamine, polyalcohol and polythiol shells, in order to best covalently bind to epoxy resins as an illustrative filled polymeric matrix.

 

[131] SIZE AND SHAPE-CONTROLLED SYNTHESIS OF AIR STABLE PBSE COLLOIDAL QUANTUM DOTS

 

Youngjin Jang1, Aldona Sashchiuk1, Efrat Lifshitz1

1 Technion; Schulich Faculty of Chemistry, Russell Berrie Nanotechnology Institute, Solid State Institute

Size and Shape-Controlled Synthesis of Air Stable PbSe Colloidal Quantum Dots
Youngjin Jang, Aldona Sashchiuk, and Efrat Lifshitz*
Schulich Faculty of Chemistry, Russell Berrie Nanotechnology Institute, Solid State Institute,
Technion, Haifa 32000, Israel

IV-VI Colloidal quantum dots (CQDs) have attracted a great attention to scientific interest and technological applications because of their unique size-dependent optical and electronic properties. Recently, the interest of CQDs exhibiting the optical properties which are active in near-infrared (NIR) (0.75-1.4 μm) and short wavelength infrared (SWIR) regime (1.4 -3 μm) is gradually growing because NIR and SWIR region are highly important for optoelectronic and imaging applications such as a photodetector and a night vision. However, the study of IV-VI CQDs that exhibit in NIR and SWIR range has been rarely done, therefore, it is still challenging. In addition, the synthesis of air stable IV-VI CQDs is highly crucial for diverse applications because IV-VI CQDs are prone to oxidation under ambient atmosphere. I present a colloidal synthesis of PbSe CQDs having the absorption in NIR and SWIR region. The size control of PbSe CQDs is achieved by adjusting the reaction temperature and the stability of PbSe CQDs against air is improved by halide treatment.

 

[136] NANOMETRIC OXIDE COATING ON POLYETHYLENE

 

Yacov Carmiel1, Chaim Sukenik2

1 Bar Ilan University; Department of Chemistry
2 Bar-Ilan University; Department of Chemistry

Nanometric oxide coating on Polyethylene
Polyethylene is widely used in the industry due to its low cost and good mechanical properties. However, its low surface energy makes it unsuitable for coating and painting. Nanometric layers (5-100 nm) of various metal-oxides have been deposited on high density polyethylene (HDPE), improving its long term hydrophilicity. The oxides were deposited by 2 methods: Liquid phase deposition (LPD) for TiO2 and SnO2, and atomic layer deposition (ALD) for TiO2, Al2O3, and ZnO. The oxide layer is very robust, as has been shown by mechanical testing of the coating. The oxide layer improves the wetting of the surface and enables adhesion of paints and other adhesives. The growth rate of the oxides was assessed by ellipsometry for the ALD deposited oxides, and by FIB-SEM cross section for the LPD deposited oxides.

 

[142] UNDERSTANDING THE MECHANISM OF INTERACTIONS BETWEEN A 12MER PEPTIDE AND HYDROXYAPATITE CRYSTALS USING SINGLE MOLECULE FORCE SPECTROSCOPY

 

tal duanis-assaf1, Meital Reches2

1 Institute of Chemistry, Hebrew University; Center for Nanoscience and Nanotechnology, Hebrew University
2 The Hebrew University of Jerusalem; The Center for Nanoscience and Nanotechnology

Understanding the mechanism of interactions between a 12mer peptide and hydroxyapatite crystals using single molecule force spectroscopy
Duanis-Assaf T., Reches M.
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem.
Human hard tissues such as bones and dentine are composed of an organic-inorganic composite material containing an organic phase of mainly collagen-I fibrils and hydroxyapatite (HAp) crystals. Such biological composites are formed in processes of self-assembly referred to as biomineralization. The processes of biomineralization are not yet completely understood, however, they are thought to be governed by the surface interactions between the organic and inorganic phases. The mechanism of adhesion of organic molecules to inorganic surfaces is not clear. Before major breakthroughs are achieved in engineering new organic-inorganic hybrid materials, further investigation of this mechanism is required.
The purpose of this study is to investigate the interactions between a peptide and HAp as a model for the organic-inorganic hybrid material in human bone tissue.
The interaction between HAp tablets and a 12mer peptide which is known to adhere to HAp was investigated using single molecule force spectroscopy (SMFS) using atomic force microscope (AFM).

 

[146] SHAPE-DEPENDENCE OF CONTACT STABILITY OF METAL NANOPARTICLE-CARBON COMPOSITE FOR ENERGY AND BIOMEDICAL APPLICATIONS

 

Mary Clare Escano1

1 Graduate School of Engineering; University of Fukui

Shape-dependence of contact stability of metal nanoparticle-carbon composite for energy and biomedical applications

Mary Clare Sison Escaño
Graduate School of Engineering, University of Fukui, 3-9-9 Bunkyo, Fukui, 910-8507 Japan

Metal nanoparticle (NP) synthesis methods have been improving recently especially in terms of achieving control over structural properties including shape. Moreover, the metal NP – carbon composite is widely used in future power devices such as fuel cell and in biomedical applications such as drug delivery. However, the contact stability of the NP-carbon composite based on shape has not been understood.
In the conference, the most stable NP will be presented based on computational simulation of 1-2nm Pt nanoparticles on carbon. The computational simulation method is based on density functional theory (DFT) conducted on larger scale to accommodate both atomistic and electronic properties of more realistic NP-carbon sizes. Using these comprehensively studied properties, the predictor of the contact stability of NP-carbon composite material is derived. Such stability predictor allows inventors, experimentalists and computational simulation researchers alike to obtain quick stability information of NP-carbon systems without the need for intensive structural property tests.

Reference:
MCS Escaño. NanoResearch 2015 8, 1689-1697.

 

[153] CONTROLLING THE SHORT-RANGE ORDER OF AMORPHOUS OXIDES BY NANOMETER SIZE

 

Yael Etinger-Geller1, Alexander Katsman2, Boaz Pokroy1

1 Technion; Department of Materials Science and Engineering
2 Department of Materials Science and Engineering, Technion − Israel Institute of Technology; Nr

Amorphous materials, in contrast to crystalline ones, lack long-range order. Its order decays rapidly with the distance; yet, the local environment for a particular type of atom is quite similar – though not identical. These fine changes in the atomistic structure of the materials lead to new and very interesting phenomena which are unique for amorphous materials. Although many aspects of science and technology rely on amorphous materials, much less research is conducted about their structure than on their crystalline counterparts.
In nature there are many organisms that use crystallization via an amorphous phase in order to achieve controlled mineralization. One of the main advantages of this method is that it enables the organism to exert control over the resulting polymorph, which is not necessarily the thermodynamic stable one.
We chose atomic layer deposition (ALD) as our material deposition method, since it is a technique that can provide extremely precise, sub-nanometric, thickness control and can deposit conformal and pinhole-free amorphous films of various materials.
It was shown lately in our group that indeed the short-range ordering changes as a function of size in amorphous aluminum-oxide. The results show that the surface of the amorphous alumina possesses a different short-range order than the average in its bulk, so the thinner the amorphous solid is, the more its short-range order resembles that near the surface
In this research we continue the study on how size affects the short-range order of different amorphous systems and correlate these changes to different properties. We believe that this amazing strategy if adopted for man-made materials could revolutionize many technological applications.

 

[155] MAXIMYZING THE POTENTIAL OF LAYERED COMPOUNDS FOR HYDROGEN PRODUCTION

 

Oren Meiron1, Lothar Houben2, Maya Bar Sadan3

1 Ben Gurion University; Ben Gurion University
2 Weizmann Institute of Science; Weizmann Institute of Science
3 Ben Gurion University ; Ben Gurion University

Maximyzing the potential of layered compounds for hydrogen production
Oren E. Meiron1, Houben Lothar2, Maya Bar-Sadan1
1Ben Gurion University of the Negev, the chemistry department, Beer Sheba, Israel
2 Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
Abstract: Layered transition metal dichalcogenides (TMDs) gained much attention in recent years. Layer edges were identified as the catalytic sites, making edge oriented morphologies a desired design. In addition, first principle calculations showed that doping and alloying of TMDs can be used to modify their electronic properties. To date, TMD alloying is primeraly performed at high temperature, solid state reactions, such as chemical vapor deposition (CVD) or chemical vapor transport (CVT) which limit morphology and composition control. We used low temperature, controllable colloidal synthesis to produce nanoflower alloyed TMDs. Specifically Mo(SxSe1-x)2 nanoflowers with edge oriented nanostructures. A range of alloy compositions were prepared. The Materials were analyzed using TEM, XRD, UV-Vis, ICP-MS spectroscopy and electron tomography. We found that the produced nanoflowers were molybdenum rich, in agreement with previous reports. The composition closely follows the feed ratio enabling the production of precisely controlled compositions. XRD and UV-Vis spectra results suggests the formation of a homogeneous solid solution rather than two separate phases of MoS2 and MoSe2. Tunable bandgap was achieved as a function of alloying degree, as measured by UV-Vis. Time series analysis results support a growth mechanism of fast-precipitating amorphous material, followed by crystallization of a few layers of small sheets, which curl and tangle around themselves. We have demonstrated the synthesis of improved edge oriented alloys using simple colloidal technique. By controlling the alloying degrees, the electronic properties of the TMDs can be optimized for a variety of applications such as photo catalysis, optoelectronics, transistors and many others.

 

[168] STRUCTURAL AND CHEMICAL TEMPLATING OF ATOMIC LAYER DEPOSITION OF AL2O3

 

Noga Kornblum1, Oleg Kreinin1, Maria Koifman2, Boaz Pokroy1

1 Technion; Department of Materials Science and Engineering
2 Department of Materials Science and Engineering, Technion − Israel Institute of Technology; Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology

Atomic layer deposition (ALD) is a method used to deposit high-quality conformal thin films.
The most prominent feature that makes the ALD technique different among the alternative growth methods is its self-limiting characteristic which enables control over the thickness and the composition of the grown film, as well as high conformality and uniformity of the film.
ALD has gained its fame during the mid. 90’s, when the semiconductors industry decided to utilize its abilities in the pursuit after smaller devices dimensions. Nevertheless, the specified advantages of this method were found highly useful for other fields, such as in optoelectronic devices, catalytic cells, nanotechnology, etc., and can be found in many different industries nowadays.
Current processes for selective thin films patterning such as photolithography, are tremendously expensive, complicated and demand special equipment and training. Therefore, there is a need for more available methods for this purpose.
In this work, we study the effect of structural surface modification using high surface energy sites, as well as chemical modification, on the selectively deposited thin alumina films. We believe that this methodology might open new ways to selectively deposit thin films without the need to perform several fabrication steps such as photolithography and etching.

 

[172] SURFACE AND BULK: ARE THEY ALWAYS THE SAME? X-RAY PHOTOELECTRON SPECTROSCOPY STUDY.

 

Tatyana Bendikov1, Delina Barats-Damatov2, Burkhard Butschke2, Jonathan Bauer2, Juan Pellegrino Morono2, Thomas Zell2, Ronny Neumann2, David Milstein2

1 Weizmann Institute of Science; Department of Chemical Research Support
2 Weizmann Institute of Science; Department of Organic Chemistry

Surface And Bulk: Are They Always The Same?
X-ray Photoelectron Spectroscopy Study.

Tatyana Bendikov1, Delina Barats-Damatov2, Burkhard Butschke2, Jonathan Bauer2,
Juan Pellegrino Morono2, Thomas Zell2, Ronny Neumann2, David Milstein2

Departments of 1Chemical Research Support and 2Organic Chemistry,
Weizmann Institute of Science, Rehovot 76100, Israel
e-mail: [email protected]

X-ray Photoelectron Spectroscopy (XPS) is a surface sensitive technique (top 10-15 nm) with sensitivity down to single atomic layer. XPS provides unique information about elemental composition and on the chemical and electronic state of the element in the material. The importance of XPS analysis is essential when the top surface and bulk of the material are different in chemical composition and, consequently, in their properties.
We present here two systems where XPS analysis shows significant differences in elemental composition of the top surface, compared to bulk material characterized by various analytical techniques, such as X-ray crystallography, NMR, EPR, Raman and infrared spectroscopies, etc.
In the first system, influence of temperature on the crystal packing and secondary structure of phosphovanadomolybdic acid, H5PV2Mo10O40 was studied.1 After high temperatures treatment (400-600C) XPS analysis reveals enrichment of the top surface of the H5PV2Mo10O40 by amorphous vanadate/phosphate layer.
In the second system, series of iron-PNN complexes were synthesized and characterized in terms of their stability, elemental composition and metal center oxidation state.2-3 Using example of two complexes, [(tBuPNN)Fe(NO)2]+[BF4]- and [(tBuPNN)Fe(NO)¬2]2+2[BF4]-, PNN= 2-[(Di-tert-butylphosphinomethyl)-6-diethylaminomethyl)pyridine, it is shown by XPS study that NO ligands are not stable and easily escape from the complex. This reveals changes in structure and in paramagnetic/diamagnetic behavior of these complexes.

1. Barats-Damatov D., Shimon L.J., Feldman I., Bendikov T., Neumann R. Inorg. Chem. 2015, 54, 628-634.
2. Zell T., Milko P., Fillman K.L., Diskin-Posner Y., Bendikov T., Iron M.A., Leitus G., Ben-David Y., Neidig M.L., Milstein D. Chem. Eur. J. 2014, 20, 4403-4413.
3. Butschke B., Fillman K.L., Bendikov T., Shimon L.J., Diskin-Posner Y, Leitus G., Gorelsky S.I., Neidig M.L., Milstein D. Inorg. Chem. 2015, 54, 4909-4926.

 

[180] GUIDED GROWTH OF HORIZONTAL ZNSE NANOWIRES AND THEIR INTEGRATION INTO HIGH-PERFORMANCE BLUE-UV PHOTODETECTORS

 

Eitan Oksenberg1, Ronit Popovitz Biro2, Katya Rechav2, Ernesto Joselevich3

1 Materials and Interfaces; Weizmann Institute of Science
2 Department of Chemical Research Support; Weizmann Institute of Science
3 Department of Materials and Interfaces; Weizmann Institute of Science

The organization of nanowires on surfaces is one of the main obstacles toward their large-scale integration into functional devices. Recently, our group developed a new bottom-up approach of “guided growth” (Science 2011, 333, 1003), demonstrating horizontal growth of nanowires along specific directions of a substrate, producing perfectly aligned arrays of nanowires. Horizontal growth of semiconductor nanowires has been implemented with several materials and substrates, but to date, none of them have band gap energies in the visible range on a transparent substrate, such as needed for optoelectronic applications. In the present manuscript, we report the guided growth of horizontally aligned ZnSe nanowires with either wurtzite (hexagonal) or zincblende (cubic) structure and different crystallographic orientations, which are exquisitely controlled by the epitaxial relations with different planes of sapphire. This is, to the best of our knowledge, the first report of horizontal nanowires of a visible-range optoelectronic material on a transparent substrate. The guided growth enables the parallel integration of the nanowires of this important optoelectronic material into blue-UV photodetectors, exhibiting the lowest dark current and the fastest measured rise and decay times for devices based on ZnSe 1D nanostructures.

 

[181] ANTIBIOFOULING SURFACE MODIFICATION OF SYNTHETIC POLYMERS WITH FUNCTIONAL SILICA NANOPARTICLES

 

Yonit Boguslavsky1, Yulia Gololobova2, Moshe Shemesh1, Elena Poverenov3

1 Agriculture Research Organization – Volcani Center; Agriculture Research Organization – Volcani Center
2 Agriculture Research Organization (Aro) – Volcani Center; Agriculture Research Organization (Aro) – Volcani Center
3 Agricultural Research Organzation (Aro); Postharvest and Food Sciences, Food Quality and Safety

Antibiofouling surface modification of synthetic polymers with functional silica nanoparticles
Boguslavsky Yonit, Gololobova Yulia, Shemesh Moshe, Poverenov Elena
Department of Food Quality and Safety
Agriculture Research Organization (ARO) – Volcani Center, Bet Dagan, Israel
Polyethylene (PE) , polystyrene (PS) and polyvinyl chloride (PVC) are among the most prevalent polymers that are used in all areas of modern life, ranging from various packaging material to medicinal equipment. However, polymer surfaces are most prone to bacterial colonization that causes adverse effects in various areas, resulting in contamination of medical devices, food contamination and biofouling. Therefore it is necessary to perform antibiofouling surface modification of these polymer films. Indeed chemical inertness of these polymers may significantly limit their versatility in surface modification, so here we present a novel non-invasive and effective method for surface modification of the synthetic polymer films with silica nanoparticles. Silica nanoparticles were created on the surface of the polymer films via tetraethyl orthosilicate (the precursor) adsorption and further silica nanoparticles growth by base catalyzed sol-gel method. The obtained silica NPs will serve as anchors for subsequent covalent attachment of antimicrobial agent, for example, contact active agent as quaternary ammonium salt (QAS). The modified films were characterized by SEM, FTIR and XPS techniques and preliminary biological evaluations were performed.

[183] NANOFILMS FOR ENHANCED PERFORMANCE OF MICROFLUIDIC DEVICES

Mirit Hen1, Chaim Sukenik2, Doron Gerber3

1 Bar-Ilan University; Institute for Nanotechnology and Advanced Materials-Bar Ilan Univrtsity
2 Bar-Ilan University; Department of Chemistry
3 Bar-Ilan University; Institute for Nanotechnology and Advanced Materials-Bar Ilan University

Nanofilms for enhanced performance of microfluidic devices
Mirit Hen1,2, Doron Gerber2,3,Chaim N. Sukenik1,2
1 Department of Chemistry, Bar-Ilan University, Ramat-Gan, 52900, Israel
2 Bar-Ilan Institute of Nanotechnology & Advanced Materials (BINA), Ramat-Gan, 52900, Israel
3 Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel

Microfluidic-based protein arrays are promising tools for life science research and development. They often provide increased sensitivity and specificity. We report the use of both organic and inorganic nanometric films for enhanced performance of microfluidic devices. These efforts focus on two areas: down-scaling the devices and developing new approaches for stable protein attachment within the device channels.
The down-scaling requires finding ways to enable the devices to withstand the higher internal pressure that will result from smaller microfluidic channels. To this end, we fabricate microstructured surfaces that improve water mobility within the channels of the device by decreasing the resistance to solvent flow. This is based on the creation of an inorganic layer that provides a template for enhanced surface hydrophobicity.
To fully optimize this system, these structures are combined with surfaces that have been shown to provide for stable, specific binding of proteins. As a general approach to stable protein attachment, we have developed a general method that involves depositing siloxane-anchored self-assembled monolayers based on 1-undecyl-thioacetate-trichlorosilane (C11TA). We successfully demonstrated the ability to produce, within an integrated microfluidic channel, a C11TA monolayer with a covalently conjugated antibody. The surface functionalization chemistry can be included as part of the fabrication of the device, thus eliminating the time consuming step of surface functionalization at the beginning of each protein array experiment.

 

[190] SELF-ASSEMBLY OF AZIDE CONTAINING DIPEPTIDES

 

Sivan Yuran1, Yair Razvag1, Priyadip Sas1, Meital Reches1

1 The Institute of Chemistry; The Center for Nanoscience and Nanotechnology

Self-assembly of azide containing dipeptides

Sivan Yuran, Yair Razvag, Priyadip Das and Meital Reches
Institute of Chemistry & the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Israel
In nature, complex functional structures are formed by the self-assembly of biomolecules such as amino acids, nucleic acids and phospholipids under mild conditions. Understanding the forces that control self-assembly and mimicking this process in vitro will bring to major advances in the area of materials science.
Peptides, specifically, hold a great promise as biomolecular building blocks since they present substantial diversity, their synthesis in large scale is straightforward, and they can be easily modified with biological and chemical entities.
We present the self-assembly of three aromatic dipeptides containing an azide moiety: H-Phe(4-azido)-Phe(4-azido)-OH, H-Phe(4-azido)-Phe-OH, and H-Phe-Phe(4-azido)-OH. The peptide H-Phe(4-azido)-Phe(4-azido)-OH self-assembled into porous spherical structures, whereas the peptides H-Phe(4-azido)-Phe-OH and H-Phe-Phe(4-azido)-OH did not form any ordered structures under the examined experimental conditions. The azido group of the peptide can serve as a photo cross-linking agent upon irradiation with UV light. To examine the effect of this group and its activity on the self-assembled structures, we irradiated the assemblies in solution for different time periods. Using electron microscopy, we determined that the porous spherical assemblies formed by the peptide H-Phe(4-azido)-Phe(4-azido)-OH underwent a structural change upon irradiation. Moreover, using indentation experiments with atomic force microscopy, we showed that the Young’s modulus of the spherical assemblies increased after irradiation with UV light. These ordered assemblies or their peptide monomer building blocks can potentially be incorporated into other peptide assemblies to generate stiffer and more stable materials or to serve as a functional group and react easily to bind a variety of materials.

 

[197] NANOSCALE OXIDATION AND REDUCTION OF GRAPHENE

 

Wei-Yen Woon1, Jonathon White2

1 Dept of Physics; National Central University
2 Dept of Photonics Engineering; Yuan Ze University

The properties of Graphene, a unique two dimensional (2D) honeycomb lattice consisting sp2 bonded carbon atoms, is affected greatly by defects. On the one hand, the presence of defects can be seen as detrimental to the electrical performance of graphene, e.g., lowering electron mobility due to scattering, and thus something to be avoided. On the other hand, defects can be employed to tailor the electrical and chemical properties of graphene. Band gap opening and reactivity modification by functionalization with foreign atoms or structural defects are good examples of the utilization of defects in graphene. The controlled formation and elimination of these nanoscale defects is the topic of this paper. Scanning probe lithography (SPL) was employed under ambient conditions to locally oxidize CVD grown graphene. Subsequently, focused soft x-ray beams were used to reduce these sub-micron sized defects. Key aspects of the process were monitored using a combination of micro-Raman spectroscopy (μ-RS) and micro-x-ray photoelectron spectroscopy (μ-XPS). and various modes of atomic force microscopy (AFM). Locally areas of oxidation – whether protrusions or depressions –always had similar spectroscopic signatures, i.e, a reduced distance between defects (μ-RS), and the appearance of C-O and C=O bonds (μ-XPS). No evidence of the generation of sp3-type defects or C-OH bonds were found. After a subsequent reduction, the graphene film was found to be chemically identical (μ-XPS) but structurally different (μ-RS) from the original graphene. During reduction, the concentration of C-O and C=O bonds decreased uniformly as the C=C bonds concentration increased. The concentration of the C-C bond was found to initially increase and then decrease. Finally by modeling the dynamics of the C=O→C–O→C–C→C=C reduction process with four coupled-rate equations and three rate constants, the conversion from C–C to C=C bonds was found to be the limiting rate for the reduction process.

 

[201] EFFICIENT ELECTRODES VIA SELF-ASSEMBLY OF GOLD NANOSTRUCTURE POROUS NETWORK

 

Ahiud Morag1, Tatiana Golub2, James Becker3, Raz Jelinek4

1 Ben-Gurion University; Ilse Katz Institute for Nanoscale Science and Technology
2 Ben-Gurion University; Chemistry Department
3 Ben – Gurion University; Chemistry Department
4 Chemistry Department ; Ilse Katz Institute for Nanoscale Science and Technology

In this work we present a gold complex self-assembled to a mesh of nanowires which function as a porous electrode. We show that a simple chemical process for the removal of the complex ligands results in a highly conductive metallic gold electrode, which contain macro- and mesoporous structure. Using cyclic voltammetry, the specific surface area of the assembly was significant, measured to be around 4 m2/g. The surface area of the electrode is only depended upon the amount of gold complex used, and gold deposition could be done on any substance and surface geometries, making it easy to integrate the electrode in electronic device. This work present a new method for the fabrication of high surface area gold electrode which is robust, cheap, and show high performance in terms of active surface area.

 

[205] CHARGE TRANSPORT IN CU2S NANOCRYSTALS ARRAYS: EFFECTS OF CRYSTAL SIZE AND SURFACE COATING

 

Orian Elimelech1 Yehonadav Bekenstein, Kathy Vinokurov, Amitai Oren, Oded Millo, Uri Banin

1 Yehudit Birk 6; 12

Nanocrystals (NCs) can be used as building blocks for new structures and devices. Considering their chemical properties and the interactions between them, a well-organized nanocrystal array with the desired features can be designed. In addition, by tuning the properties of NCs arrays, applications in transistors, solar cells, sensors, and biosensor are enabled.
Copper (I) sulfide semiconductor have a wide spectrum of interesting properties, while one of them is related to being a mother compound to a larger family of ternary and quaternary Cu based semiconducting materials. NCs of such earth abundant materials are important in photovoltaic applications, considering their relevant band-gap values and their environmental compatibility.

In our work, we have studied how crystal size affects charge transport in Cu2S NCs arrays. Two NCs sizes were studied- 3 nm being within the quantum-confinement regime, and 14 nm, lacking quantum confinement. Additionally, the particles surface coverage was also modified with different ligands and the effect of their length on the charge transport mechanism was studied via temperature dependent conductance measurements. While in the 14nm NC based devices unique non-monotonic temperature dependence was observed, the 3nm based devices showed only thermally activated transport for all ligands. The difference was attributed to a cross-over from inter-particle hopping to intra-particle dominated transport as the ligand length increases. The presented new data has direct implication on the design of future Cu based NC devices.

Reference: Bekenstein, Y., Elimelech O., Vinokurov, K.,Millo, O., Banin, U., Charge transport in Cu2S nanocrystal arrays; a study of crystal size and ligand length, Zeitschrift für Physikalische Chemie (2014) doi: 10.1515/zpch-2014-0593

 

[211] NANOMANUFACTURING FOR DURABLE SUPERHYDROPHOBIC/ICEPHOBIC COATINGS

 

Joey Mead1, Tehila Nahum1, Artee Panwar1, Hanna Dodiuk2, Carol Barry1, Shmuel Kenig 2

1 University of Massachusetts Lowell; 1 University Avenue
2 Shenkar College; Anna Frank 12

Ice adhesion to surfaces is a significant problem with aircraft, ships, and power lines. The use of superhydrophobic surfaces for anti-ice properties have shown that they can reduce ice adhesion strength significantly compared to bare aluminum surfaces, but lack durability. Superhydrophobicity can be obtained by tailoring the chemistry and the roughness of the surface, mimicking the lotus leaf. Most superhydrophobic surfaces lose their roughness in harsh conditions and are unsuitable for practical applications. Typical superhydrophobic surfaces have micro-nano hierarchical roughness and hydrophobic chemistry. We have created several cost-effective, durable, and easily-manufacturable solutions to create icephobic surfaces on existing aircraft, ships, and power lines. The first approach uses particles in a polymer matrix to achieve superhydrophobic surfaces. The coating can be applied easily to large surfaces by spray coating and can be used with a variety of polymer matrices. A secondary top down approach can also be used for replicating nanostructured surfaces into thermoplastic films. Results for both approaches indicate the formation of superhydrophobic surfaces (contact angle >150° and sliding angle < 10°) with improved durability. The process can be scaled to a roll to roll process for large area applications.

 

[213] ELECTROCHEMICAL DEPOSITION OF NANOSTRUCTURES ON STRIPED PATTERNS OF BLOCK COPOLYMER TEMPLATE

 

Chanchayya Chandaluri1, Gilad Pelossof1, Ran Tel-Vered1, Roy Shenhar1, Itamar Willner1

1 The Hebrew University of Jerusalem; Givat Ram

Electrochemical Deposition of Nanostructures on Striped Patterns of Block Copolymer Template

Chanchayya Gupta Chandaluri, Gilad Pelossof, Ran Tel-Vered, Roy Shenhar* and Itamar Willner*
Institute of Chemistry, The Hebrew University of Jerusalem, Israel.

Patterned functionalized surfaces are of considerable interest due to a wide range of applications, from sensors and catalysts to photonic devices, which benefit either from the high surface area or from the nanoscale pattern. However, obtaining nano-patterned surfaces in a controlled fashion is not trivial. Block copolymers – polymers consisting of sequences of chemically distinct repeat units – give rise to useful nanoscale morphologies in thin films by phase separation, and thus provide a powerful platform for nano-patterning.
The poster describes our approach for obtaining nano-patterned functional coatings on electrodes using block copolymer films as masks. We show that chemical modification of one type of domains leads to substantially increased affinity of redox species to these domains. This enables selective electrodeposition of nanomaterials on these domains. Using this approach, we exemplify the ability to tune the wetting properties of the coated electrode by controlling the amount of deposited material on it, and demonstrate the crucial role of the nano-pattern.

 

[215] CELLULOSE COATED OIL-IN-WATER AND WATER-IN-OIL EMULSIONS REVEALED BY MOLECULAR DYNAMICS SIMULATIONS

 

Hitomi Miyamoto1, Dmitry Rein1, Chihiro Yamane2, Kazuyoshi Ueda3, Yachin Cohen1

1 Technion – Israel Institute of Technology, Department of Chemical Engineering; Technion City
2 Kobe Women’s University, Faculty of Home Economics; 2-1 Aoyama, Higashisuma Suma-Ku
3 Yokohama National University, Graduate School of Engineering; 79-5 Tokiwadai, Hodogaya-Ku

Encapsulation is an important technique which can provide many useful properties with small capsules. It is known that cellulose molecules dissolving in ionic liquid and cellulose in the amorphous state in hydro-gels regenerated from the solution form a stabilizing coating for oil-in-water and water-in-oil emulsions. However, the stability process and the coating state in molecular levels have not yet been fully understood. This study investigated the behavior of cellulose in oil-in-water and water-in-oil using molecular dynamics (MD) simulation.
Two different cellulose models were used respectively as initial models for oil-in-water and water-in-oil: one model consists of 16 separated chains of cellulose, and the other consists of cellulose mini-crystal constructed using the crystal coordinates of cellulose II. Octane molecules were used as the oil in this study. MD simulations were performed using CHARMM37 with CHARMM35 force field specifically developed for carbohydrates. The system was equilibrated at 300 K and 1 bar for 50 ns in NPT ensemble.
In both cellulose models for oil-in-water system, several oil droplets gathered to form one oil droplet at the beginning of simulations, and a single oil droplet apparently remained unchanged during 50 ns simulations. In the simulation model of 16 separated cellulose chains, the chains were gradually assembled with the progress of simulation time. Then, the octane droplet was observed to be surrounded by cellulose chains. These cellulose chains linked together by intermolecular hydrogen bonds. In the case of cellulose mini-crystal model for oil-in-water system, the structure of cellulose mini-crystal model was almost unaltered during the simulation. The cellulose chain on the corner along the (110) crystal plane which has a hydrophobic surface in the mini-crystal first interacts with octane molecules, and the cellulose chains along the plane then gradually interact with octane molecules during 50 ns simulations. In both cases of cellulose models for water-in-oil system, all water molecules interact with cellulose chains and they form hydrogen bonds at the beginning of simulations.

 

[225] SPACE DURABLE CNT-BASED NANOCOMPOSITES

 

Nurit Atar1, Eitan Grossman1, Irina Gouzman 1, Asaf Bolker1, Yael Hanein2

1 Space Environment Department; Soreq Nrc
2 Center for Nanoscience and Nanotechnology; Tel Aviv University

Polyimide (PI) is extensively used in various space applications due to its chemical and radiation resistance as well as its thermal stability. In particular, PI is commonly used as an exterior layer of thermal control blankets that are aimed to maintain a spacecraft’s instrumentation at working temperature. However, PI is degraded by electrostatic discharge (ESD) and atomic oxygen (AO), which are the dominant space environment hazards in geo-synchronous Earth orbit (GEO) and low Earth orbit (LEO), respectively. A common solution to this challenge is to coat the outer PI layer with indium tin oxide (ITO) which is AO resistant and electrically conductive and can therefore prevent local voltage build-up. However, ITO coatings are extremely brittle and cannot tolerate folding or bending when applied to flexible spacecraft surfaces. In this research, electrically-conductive PI-based composites for ESD protection were prepared by infiltration of PI-based blends into chemical vapor deposition (CVD)-grown carbon nanotube (CNT) sheets. AO durability was attained by the addition of polyhedral oligomeric silsesquioxane (POSS) to the PI precursor. This method prevents CNT agglomeration and degradation of the CNT properties. CNT-POSS-PI films with varying POSS content (0, 5, and 15 wt%) were prepared and exhibited homogeneous CNT distribution within the PI-based matrix. The composite films demonstrated sheet resistivities as low as 200 Ω/□, essentially preserving the original CNT sheet resistivity and well satisfying the ESD criterion. These resistivities remained essentially unchanged after mechanical manipulation, thermal cycling, and exposure to ionizing radiation. CNT-15%POSS-PI films exhibited an erosion yield of roughly one order of magnitude lower than that of pure PI films, and hence a 20 µm thick film could be functional for more than 10 years in the AO environment at LEO altitudes. CNT-PI and CNT-15%POSS-PI films are suggested for space applications such as the outer layers of spacecraft thermal blankets.

 

[227] CONTROL AND MANIPULATION OF QUANTUM SWITCHING AND SPIN-SPIN CORRELATIONS OF ENTANGLED NANOQUBIT PAIRS IN TB2 MOLECULAR MAGNET FOR INFORMATION PROCESSING

 

Oleg Farberovich1, Vyacheslav Gritzaenko2

1 Tel Aviv University; Tel Aviv University
2 Southern Federal University; Southern Federal University

Control and manipulation of quantum switching and spin-spin correlations of
entangled nanoqubit pairs in Tb2 molecular magnet for information processing

The problem of the spin switching speed of today magnetic logic and a magnetic memory devices into the terahertz regime underlies the entire field of information
processing. The physics of present-day devices imposes serious limitations on this technological transformation, so we must invent new paradigms based on
the quantum spin dynamics in the picosecond regime. This challenge could be met by a simulation of the quantum spin switching in a picosecond pulsed magnetic field.
We will discuss the relevance of the compound [Tb2Cl(HL4)2(H2L4)(py)2]. The studying of a possibility of the switching of the spin states and a controling of the entanglement would incredibly increase the amount of information storable with respect to current devices. In order to have a deeper understanding of fundamental features and a major control on technological aspects, the time-dependent spin dynamics constitutes the key point. The micromagnetic model describes appropriately the dynamics of the spin in a magnetic nanostructures. The spin dynamics are described by the Landau-Lifshitz-Gilbert (LLG) equation.
Spin systems are directly related to the entanglement between different spins, which can be employed in the field of quantum information processing. So far much of the work on correlations has focused on the static properties of equilibrium systems. It has been revealed that the way entanglement is created and how it propagates are important fundamental questions in quantum information theory. We will consider to what extent it is possible to control and manipulation of the correlation functions and entanglement by the pulse magnetic field. This may be relevant for the optimal creation of entanglement in spin systems, as well as contributing to a better understanding of how correlations are created in dynamical processes, something that can be tested experimentally in present setups.

 

[231] DIRECTIONAL COLLOIDAL SURFACE TREATMENT IN MICROFLUIDIC DEVICES

 

Eitan Edri1, Silvia Piperno2, Hagay Shpaisman3

1 Bar-Ilan University; Nano Technology Institute
2 Chemistry Department.; Bar Ilan University
3 Bar Ilan University; Nanotechnology Institute

Directional Colloidal Surface Treatment in Microfluidic Devices
Eitan Edri, Silvia Piperno, Hagay Shpaisman
The Nanotechnology Institute, Chemistry Department, Bar-Ilan University, Ramat-Gan, Israel

A novel concept is hereby demonstrated where directional surface treatment is performed on polymeric colloids by using a PDMS microfluidic device. In recent years, PDMS based microfluidic technology has become a great tool for complex micro-particle generation, thanks to its design flexibility. Therefore, we designed and fabricated a unique microfluidic device that can generate polymeric colloids by emulsification of a liquid monomer and treat their surface at specific locations. The treatment is performed by a small quantity of solution that is added to a specific location on the particle.
The novelty of this technique is in its potential to treat the same particle with different precursors in different directions resulting in the formation of patchy particles. These patchy particles will have the ability to bind to each other with a specific arrangement via different directional treatments. As the directionality could be easily programmable, numerous structures could be assembled.

 

[232] CHEMICAL EPITAXY AND REACTIVITY IN SOLUTION DEPOSITED PBS ON ZNTE FOR POTENTIAL USE IN SOLAR CELLS

 

sucheta sengupta1, Tzvi Templeman2, Yuval Golan1

1 Ben Gurion University of Negev; Marcus Family Campus
2 Ben-Gurion University ; Department of Material Engineering

Chemical epitaxy and reactivity in solution deposited PbS on ZnTe for potential use in solar cells

Sucheta Sengupta, Tzvi Templeman and Yuval Golan

Despite their promise, the efficiency of quantum dot solar cells is currently low (< 10%), where improved understanding of interfaces and contact layers adjacent to the quantum dots are presently a major limitation. The present work aims at optimizing the chemical bath deposition conditions for growing PbS thin films on MBE grown ZnTe for solar cell design. The morphology and properties of these films are found to be strongly affected by altering the solution pH, temperature and the reagent concentrations. A detailed structural analysis reveals the different orientation relationships present between the constituent layers and highlights the spontaneous formation of new, distinct intermediate layers during deposition. We also demonstrate that depending on the growth mechanism, the epitaxial informations are transmitted differently from one layer to the other under different conditions resulting in films with different orientations.

 

[245] TOWARDS ARTIFICIAL DNA MOLECULAR MOTORS THAT CAN WALK OVER MICROMETERS

 

Miran Liber1, Toma Tomov1, Roman Tsukanov2, Yaron Berger3, Eyal Nir1

1 Ben-Gurion University of the Negev; Ilse Katz Institute for Nanoscale Science & Technology
2 Ben Gurion University; Ilse Katz Institute for Nanoscale Science & Technology
3 Ben-Gurion University; Ilse Katz Institute for Nanoscale Science & Technology

Department of Chemistry and the Ilse Katz Institute for Nanoscale Science and Technology, BenGurion University of the Negev, Beer Sheva, 84105, Israel, [email protected], [email protected]

Inspired by biological molecular motors such as Kinesin, which walk on microtubules over distance of several micrometers, our group develops artificial molecular motors made of DNA. We demonstrate striding of a bipedal walker over a distance of ~ 400 nm, in a back and forth fashion, on a 90 nm long track embedded into a DNA origami. However, to enable a unidirectional walking over long distances, it is necessary to attach several origami units in a control manner and with high yield and stability.
For that purpose we study different methods for connecting DNA origami tiles to create long tracks. The binding and unbinding reactions, yields and kinetics, were measured using single-molecule fluorescence spectroscopy, and binding methods and conditions were optimized to achieve best yield and stability.
Furthermore, by comparing the processivity of a motor striding on a single origami tile to that of an identical motor striding across the gap between two attached origami tiles we demonstrate that the walker does not dissociate when crossing between the origami. Moreover, we demonstrate that dozens of origami tiles can be connected to form a stable micrometer-long track. By these means we successfully demonstrate the necessary steps towards long range, robust and reliable artificial molecular motors and machines.

 

[249] SINGLE-STRANDED DNA DETECTION BY SOLVENT-INDUCED ASSEMBLIES OF A METALLO-PEPTIDE-BASED COMPLEX

 

Priyadip Das1, Meital Reches2

1 Institute Of Chemistry; The Hebrew University of Jerusalem
2 The Institute of Chemistry; The Center for Nanoscience and Nanotechnology

Single-stranded DNA Detection by Solvent-Induced Assemblies of a Metallo-Peptide-Based Complex
Priyadip Das1,2 Meital Reches1,2
1Institute of Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
2The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel

DNA detection is highly important for the sensitive sensing of different pathogenic bacteria and viruses. The major challenge is to create a sensor that can selectively detect very small concentrations of DNA without the need for amplification or complicated equipment. Different technologies such as optical, electrochemical and microgravimetric approaches can detect DNA fragments. Here we show, for the first time, the use of self-assembled nanostructures generated by a metallo-peptide as an optical sensing platform for DNA detection. The system can selectively detect single stranded DNA fragments by fluorescent measurements as it can discriminate between one mismatch and can perform even in the presence of other interfering proteins. This system may be useful in lab-on-a-chip applications. More importantly, the lower detection limit of this system for the HIV DNA was 1.4 nM, which is lower than those sensing system based on carbon nanostructures.

 

[254] HOLLOWING KINETICS OF AG-AU CORE-SHELL NANOPARTICLES CONTROLLED BY SHORT CIRCUIT DIFFUSION

 

Nimrod Gazit1, Eugen Rabkin1, Gunther Richter2

1 Department of Materials Science and Engineering; Technion
2 Thin Films; Max Planck Institute for Intelligent Systems

Hollow metallic nanoparticles attract great deal of attention due to their possible applications in various fields of nanotechnology (drug delivery, energy production and storage, catalysis, etc.). These particles have been fabricated in the past employing wet chemistry methods or/and Kirkendall effect during bulk interdiffusion in the core-shell nanoparticles. The latter process requires relatively high temperatures at which the bulk diffusion is active.
In this work we present a method of fabricating hollow Au nanoparticles based on surface and grain boundary diffusion, similar to the method proposed earlier for producing of hollow nanowhiskers . We produced an array of single crystal Ag nanoparticles on sapphire employing the solid state dewetting process of a thin Ag film deposited on sapphire substrate. A thin polycrystalline Au film was then deposited on the dewetted sample. During subsequent heat treatment at 170 °C the Ag atoms from the core of the core-shell Ag-Au nanoparticles diffused along the short-circuit diffusion paths (as shown by EFTEM analysis), leaving behind hollow Au nanoparticles. The hollowing kinetics that were studied by scanning electron microscopy and by a combination of focused ion beam with transmission electron microscopy are presented.

 

[259] METAL DIFFUSION ALONG THE FILM-SUBSTRATE INTERFACE IN PARTIALLY DEWETTED THIN FILMS

 

Hagit Barda1, Dor Amram1, Eugen Rabkin1

1 Department of Materials Science and Engineering; Technion

In a recent work [1], an indirect evidence for fast self-diffusion of Ni along the Ni-sapphire interface has been obtained. Polycrystalline Ni films of 40 nm in thickness were deposited on sapphire substrates. Solid state dewetting and grain boundary grooving in the films were studied at 700°C. An unusual flat topography of the grain boundary grooves and homogeneous thickening of the film were interpreted in terms of fast Ni self-diffusion along the film-substrate interface [1].
Based on these results, we propose a new method of measuring the metal heterodiffusion along the Ni-sapphire interface. We deposited a 4 nm thick Au film on partially dewetted Ni film which consists of holes (dewetted areas) surrounded by a bi-crystalline film. Afterwards, a diffusion annealing was performed at the temperature of 600°C, at which the morphology of the Ni film is highly stable. Gold atoms diffused from the edge of the holes along the Ni-sapphire interface, and the concentration decay in the direction from the hole edge to the unperturbed film was quantitatively characterized by high resolution transmission electron microscopy. Based on the suggested method, diffusion coefficient of Au along a film-substrate interface was determined.

[1] D. Amram, L. Klinger, N. Gazit, H. Gluska, E. Rabkin. ”Grain boundary grooving in thin films
revisited: the role of interface diffusion”, Acta mater. 2014; 69:386.

 

[265] GUIDED GROWTH OF HORIZONTAL CDSE NANOWIRES AND THEIR INTEGRATION INTO FAST VISIBLE-RANGE PHOTODETECTORS

 

erga shalev1, Eitan Oksenberg2, Ronit Popovitz Biro3, Katya Rechav3, Ernesto Joselevich4

1 Department of Materials and Interfaces ; Weizmann Institute of Science
2 Materials and Interfaces; Weizmann Institute of Science
3 Department of Chemical Research Support; Weizmann Institute of Science
4 Department of Materials and Interfaces; Weizmann Institute of Science

One-dimensional semiconductor nanostructures, such as nanowires (NWs), have attracted tremendous attention due to their unique properties and potential applications in nanoelectronics, nano-optoelectronics and sensors. The big challenge towards their integration into practical devices is their large-scale assembly with orientation control. Recently, our group has demonstrated a new growth approach for NWs: guided growth of horizontal NWs with controlled orientations via vapor-liquid-solid (VLS) process. The growth direction and crystallographic orientation are controlled by epitaxial relationship with the substrate, as well as by a graphoepitaxial effect of surface nano steps and grooves. The grown NWs location is determined by controlled prepositioning of a catalyst. Until now, our group succeeded to grow guided NWs of GaN, ZnO and ZnSe on sapphire, and GaN NWs on SiC and quartz. In order to reveal the full potential of this approach the guided growth process must be extended to a broader range of semiconductors with a variety of electrical and optical properties. In this work we report the guided growth of CdSe NWs on five different sapphire substrates. CdSe is a direct-bandgap II-VI semiconductor active in the visible range, which enables potential applications in optoelectronic devices. The guided NWs structure was characterized; the grown NWs were found to have wurtzite single crystal structure. Field effect transistors (FETs) were built to examine the NWs electronic properties. Their optoelectronic properties were also studied revealing promising results. The guided CdSe NWs have fast rise and decay times, less than the best published for CdSe NWs, which is essential for optoelectronic applications.

 

[268] EFFECT OF BLEND SOLVENTS ON THE STABILITY OF PTB7:PCBM-BASED SOLAR CELLS

 

laura ciammaruchi1

1 Ben Gurion University of the Negev; Department of Solar Energy and Environmental Physics

EFFECT OF BLEND SOLVENTS ON THE STABILITY
OF PTB7:PCBM-BASED SOLAR CELLS
Laura Ciammaruchi1,Gloria Zanotti1,3,Francesca Brunetti2,Eugene A.Katz1,4and Iris Visoly-Fisher1,4
1.Department of Solar Energy and Environmental Physics,Ben Gurion University of the Negev,Sede Boker, Israel.
2.Dept. of Electronics Engineering,Università di Tor Vergata,Rome, Italy
3.CNR–ISM Via Salaria km29.500,Monterotondo Scalo(Rm),Italy
4.Ilse Katz Institute for Nano-scale Science and Technology,Ben Gurion University of the Negev, BeerSheva,Israel
Low-band-gap organic photovoltaic(OPV) reached significant photo-conversion efficiencies(PCEs) and the current research faces two fundamental challenges:combining adequate lifetime with low manufacturing impact on the environment.8.7%PCE was reported for an inverted OPV cell based on PTB7:PCBM blended in o-xylene(XY),eliminating the polluting chlorine in chlorobenzene(CB) commonly used as the blend solvent[1].Since the solvent choice determines the photo-active layer morphology hence charge carrier mobility,it may also affect the degradation patterns [2].We studied solvent-related degradation in inverted PTB7:PCBM-based cell blended in CB or XY.Optical, morphological and electrical investigations point to a solvent-driven vertical stratification in the photoactive layer,affecting the degradation mechanisms.PTB7-rich bottom layers were assumed in CB-cells,while PCBM-rich top layers were found inXY-cells.XY-cells showed superior stability compared to CB-cells during storage in the dark and exposure to natural sunlight.CB-cell degradation was demonstrated mostly by Voc decrease due to morphology coarsening,while XY-cell degradation was expressed in Jsc decrease, probably due to chemical degradation ofPTB7 at the interfaces.However,XY-cells were less stable under concentrated sunlight[3],due to the increased UV illumination intensity.The reduced stability is attributed to residual XY in the photoactive layer,which is UV-sensitive,and is enhanced by the top Ag contact which acts as a photocatalyst.We conclude that the improved morphology stability,combined with a more efficient solvent evaporation process and appropriate UV filtering,vote in favor of the use of more environmentally friendly,non-chlorinated solvents such as XY.

1. Susanna, G., et al., Solar Energy Materials and Solar Cells, 2015, 134: 194-198
2. Takayuki, K., et al., Japanese Journal of Applied Physics, 2014, 53.2S: 02BE06.
3. I. Visoly-Fisher, et al., Sol. Ener. Mater. & Sol. Cells 2015, 134: 99–107

 

 

 

 

 

 

[284] SINGLE MOLECULE AND NANOPARTICLE ABSORPTION SPECTROSCOPY

 

eitam vinegrad1

1 Tel-Aviv University; –

Single molecule and nanoparticle absorption spectroscopy
Eitam Vinegrad1, Ori Cheshnovsky2
1) School of Physics, Tel-Aviv University, 2) School of Chemistry, Tel-Aviv University 69978 Tel Aviv, Israel
Single molecule spectroscopic detection in fluorescent microscopy is well established now. The technique highly relies on the fact that it is practically background free. Extensive research pertaining to the dynamics of single molecules is based on single-molecule spectroscopy. However, not all molecules of interest fluoresce. In many cases, the introduction of fluorescent marker molecule is required in order to investigate or monitor the required dynamics. In other cases, the spectroscopic properties of non-fluorescent molecules cannot be studied with this technique. In the last few years, few techniques capable of single molecule detection via optical absorption have emerged. Due to the fact that the area of diffraction limited laser spot is of the order of magnitude of 0.1 µm2 and the absorption cross section of molecules is of the order of 10-7 µm2, detection capability of extremely small optical densities is required in these methods.
In this work, we present a new approach in measuring the absorption of single nano objects. We use a super-continuum laser (Fianium) and a circular variable filter to choose the wavelength of operation. The absorption detection is then carried out by balanced photodiodes aimed to suppress the laser noise.
Scientific goals:
A. Spectroscopic characterization of specially designed Si/Ge core shell nanowires (fabricated by our collaborators in F. Patolsky’s lab), which according to theoretical predictions by A. Zunger are characterized by a direct band gap.
B. Chirality measurements of single nano objects both of artificially designed chiral nano objects and chiral nanoparticles (with our collaborators in G. Markovich’s lab).
We will present our experimental methodology as well as preliminary results on the absorption of several nanoparticle systems, as well as chirality measurements of artificial nano objects.

 

[287] STUDY OF NANOLAYERS IN REVERSE LIT CONFIGURATION FOR PEROVSKITE SOLAR CELLS ON METAL SUBSTRATES

 

Maria del Carmen Lopez Luna1, S. Zaka Ahmed2, David Pickup2

1 Dyesol UK Ltd. ; 48 Grafton Street M13 9xx
2 Dyesol UK Ltd.; 48 Grafton Street M13 9xx

STUDY OF NANOLAYERS IN REVERSE LIT CONFIGURATION FOR PEROVSKITE SOLAR CELLS ON METAL SUBSTRATES

María C. López, S. Zaka Ahmed, David Pickup.
Dyesol UK Ltd. 48 Grafton Street M13 9XX Manchester UNITED KINGDOM
[email protected]

Perovskite Solar Cells (PSCs) have attracted great interest in the scientific community due to their ease of preparation and high power conversion efficiencies. Thanks to their ultra-low weight architecture and low cost manufacturing techniques, metal based PSCs could find applications on the roofs of supermarkets, warehouses, etc. PSC could act as power plants for self-energy generating buildings with off-grid or feed-in configurations.
The implementation of PSC on metal has several challenges since metals are not transparent and the light must get in through the opposite side. There is a sacrifice in performance due to reverse lit configuration since the transmittance is lower through the semi-transparent electrode and HTM/ETM than through FTO glass side.
We have calculated the loss in performance due to reverse lit configuration using glass substrates with semi-transparent gold-coatings. Before reaching the capping layer, light must pass through the thin gold coating (12-15 nm) and the HTM, which have a transmittance of 63% and 94.5% respectively in the visible light wavelength range. Consequently there is a direct lost in light ingress of 42.5% that is equivalent to a decrease in photo-generated current in the same ratio. Actually the experimental decrease in current is ≈46.7%. This might be attributed to the fact that physical phenomena taking place in reverse and normal lit configuration are not exactly the same. In reverse lit light interacts first with the capping layer whereas in normal lit it interacts first with the infiltrated perovskite in the mesoporous titania layer.

Acknowledgments
The research leading to these results has received funding from the European Union Seventh Framework Programme under DESTINY project (grant agreement 316494).

 

[290] FLEXIBLE CARBON NANOTUBES BASED ACTUATORS

 

Ela Sachyani1

1 The Hebrew University ; The Hebrew University

Flexible Carbon Nanotubes Based Actuators

Ela Sachyani, Michael Layani and Shlomo Magdassi

Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel

Actuators are devices that react by movement to a given trigger such as electric field, magnetic field, heat or light. Actuators can be used in a variety of fields such as mechanical devices, sensing, and soft robotics.
The work presented here is focused on printed electrothermal Carbon Nanotubes (CNT) based actuators. A typical electrothermal actuator structure is a double layer containing CNT electrode and a polymer. CNTs are flexible, electrically and thermally conductive, and therefore are excellent candidates for flexible and stretchable electrothermally triggered actuators.
Three main types of CNT based actuators are presented. The first type is a U-shaped CNT layer deposited on top of polyimide substrate. The actuation occurs due to a deference in thermal expansion coefficient (CTE) between the two materials. Once voltage is applied, the CNT layer heats up and the actuator bends towards the material that has smaller thermal expansion. The second type is a U-shaped CNT layer deposited on a Shape Memory Polymer (SMP) [1]. The SMP is a material that can recover its permanent shape after temporary shape deformation. Here, the CNT acts as an electrical heater that reverts the SMP back to its original state. The third type of CNT actuator is based a combination of the first and second type of actuators.
The future goal is to fabricate 3D printed actuators for the soft robotic applications.

[1] Zarek, M.; Layani, M.; Cooperstein, I.; Sachyani, E.; Cohn, D.; Magdassi, S. “3D Printing of Shape Memory Polymers for Flexible Electronic Devices”, Advanced materials 2015, DOI: 10.1002/adma.201503132.

 

[291] SOLID PHASE HYDROGENATION OF PHENYL ACETYLENES BY HYDROGEN SPILLOVER: THE IMPACT OF HYDROGENATION PRESSURE AND SPILLOVER MEDIA ON PRODUCT DISTRIBUTION

 

Adi Mary Akiva-Moyal1, Eyal Ben-Yehuda1, Michael Gozin2, Ofra Paz-Tal1, Svetlana Pevzner1

1 Nuclear Research Center of Negev; Chemistry Department
2 School of Chemistry; Ttel Aviv University

Hydrogenation in the solid phase is important in “green” synthesis, for the limited use of solvents and for the use of solid, recyclable catalysts. This reaction is also significant in the field of hydrogen scavenging, where it is necessary to remove the hydrogen gas in order to prevent the risks of explosion, metal corrosion or embrittlement, due to its reaction with hydrogen.
The catalytic solid-phase hydrogenation of two short phenyl-acetylenes was studied.
Solid samples of the acetylenes with a Pd/C catalyst were hydrogenated to various degrees at different initial pressures; the partially hydrogenated samples were separated from the catalyst and analyzed by gas-chromatography, to quantify the reaction products.
Comparison of the products’ distribution at different hydrogenation pressures and at different stages of the hydrogenation reaction, gives insight into the mechanism of hydrogenation in the solid phase.
We claim that the hydrogen travels from the metal catalyst to the substrate by a mechanism known as hydrogen spillover, that is, the hydrogen migrates across the catalyst’s carbon support.
The results of the study show that the reaction intermediates prefer syn addition; and the amounts of these products are greatly affected by the hydrogenation pressure.
Addition of carbon nanotubes to the solid reaction media was previously shown to increase the reaction rate. In this study, analysis of the influence of carbon nanotubes (CNTs) on the products’ distribution shows trends similar to the hydrogenation pressure increase. We believe that the CNTs, which are known as spillover agents, facilitate the migration of hydrogen from the metal catalyst to the solid substrate and increase the distance that activated hydrogen species can travel. This phenomenon could be described as reducing the energy barrier for the diffusion of the hydrogen species.
In summary, by studying the product distribution of the solid phase hydrogenation at different pressures with the addition of spillover agents, one gains insight into the reaction mechanism.

 

[298] INVESTIGATION OF THE WET ETCHING OF GE2SB2TE5 THIN FILMS FOR NON-VOLATILE PHASE CHANGE MEMORY APPLICATION

 

Svetlana Nemtseva1, Maria Mikhailova1, Petr Lazarenko1, Alexey Sherchenkov1, Sergey Kozyukhin2, Sergey Timoshenkov1

1 National Research University of Electronic Technology; Bld. 1, Shokin Square 124498
2 Kurnakov Institute of General and Inorganic Chemistry of Russian Academy of Science; 31 Leninsky Prospect 119991

Non-volatile phase-change memory (PCM) on the basis of Ge2Sb2Te5 (GST225) is one of the main candidates for the next generation of memory technology.
High operation rate (less than 100 ns), cyclability (>108), and possibility of using the standard processes of microelectronics are the main advantages of PCM technology. However, optimization of PCM-technology is required, particularly, of the formation of nanoscale programmable cell area. Therefore development of the etching process of GST225 thin films for the fabrication of PCM cell is needed.
Amorphous thin films were deposited on SiO2 substrate by the thermal evaporation in vacuum. The thicknesses of the films were approximately 200 nm.
Optical microscopy (Carl Zeiss Axiovert 40 MAC) and atomic force microscopy (NT-MDT SolverPro) were used to investigate morphology of thin films.
The average roughness of the film surface was 0,224 nm.
It was established that (20 vol.%) solution of HCl, H3PO4, H2SO4, did not etch as-deposited GST225 film, and according to AFM the change of of the surface was not observed. However, adding of the H2O2 (30 vol.%) to acid inert solution allowed to obtain the active etchant.
Treatment of the film in H2O2 at room temperature did not lead to the etching of the film. However, increasing of the temperature up to 30-70 °C was accompanied by the modification of the GST225 layer morphology.
One of the important photolithography operations is removing of the photoresist in DMFA (C3H7NO) solution. It was found that using of DMFA did not lead to the change in the surface morphology of GST225 film. According to ACM the average surface roughness is comparable with that of the initial morphology, so it can be used in photolithography processes.
As a result, it has been found that the Ge2Sb2Te5 thin film is easily etched with HNO3 and: H2SO4, H3PO4, HCl solutions added with H2O2.
This work was supported by the Ministry of Education and Science of Russian Federation (FPP, project ID: RFMEFI57814X0085).

 

[299] TRANSPARENT POLYCRYSTALLINE ND:YAG PROCESSED BY HIGH PRESSURE SPARK PLASMA SINTERING (HPSPS) TECHNIQUE

 

Maxim Sokol1, Sergey Kalabukhov1, Vladimir Kasiyan1, Moshe Dariel1, Frage Nachum2

1 Ben-Gurion University of the Negev; P.O.B. 653
2 Bgu; P.O.B. 653

High pressure spark plasma sintering (HPSPS) was employed to fabricate polycrystalline Nd:YAG specimens with desired functional properties. Specimens fabricated under a uniaxial pressure of 300 MPa at 1300°C at a heating rate of 50°C/min and holding time of 60 min displayed nano-structure and elevated mechanical properties, including resistance to thermal shock. Optical properties (i.e. spectral transmittance, fluorescence emission spectra and fluorescence lifetime) of the HPSPS-processed specimens were close to those obtained with specimens fabricated by conventional sintering procedure. Remarkable differences in threshold power and laser slope efficiency were found and attributed to the variance in Nd concentration in the specimens tested. The results of the present study indicate that the low cost and time-saving HPSPS process can be used for the fabrication of polycrystalline Nd:YAG specimens with the combination of the optical and mechanical properties suitable for laser applications.

 

[301] POROUS COLLOIDS GENERATED BY SPINODAL DECOMPOSITION

 

Elad Hadad1

1 Bar Ilan University Ramat Gan, 5290002; Bar Ilan University Ramat Gan, 5290002

Porous Colloids Generated by Spinodal Decomposition
Elad Hadad , Hagay Shpaisman
The Chemistry Department, Institute for Nanotechnology and Advanced Materials
Bar-Ilan University, Ramat-Gan, Israel

Spinodal decomposition (SD) is a mechanism by which a one phase solution separates into different phases with distinctly different chemical compositions, thus forming a unique porous structure. These structures have been extensively studied in thin films and bulk. Here we present a novel method where porous colloids are fabricated by SD separation. We study how the interface between the continuous phase and the dispersed phase undergoing SD influences the forming structure.
A mixture of a UV curable adhesive (NOA 81) with a co-solvent (acetone) and non-solvent (water) serves as the dispersed phase. By UV irradiation this phase undergoes photo-polymerization induced SD phase separation. We find that for maintaining SD the most suitable continuous phase requires minimal interaction with the dispersed phase (fluorocarbon oil).
We gain control over the porous structure of the colloids by controlling the dispersion method, UV intensity, temperature and the composition of the dispersed phase. Further study over the properties of these new porous colloids will follow.

 

[312] INDUCTION OF CHIRALITY AND CHIROPTICAL ACTIVITY IN INORGANIC NANOCRYSTALS USING BIOMOLEUCLES

 

Assaf Ben-Moshe1, Gil Markovich2

1 School of Chemistry; Tel-Aviv University
2 School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences; Tel-Aviv University

Chirality is a geometric property of objects that cannot be superimposed onto their mirror images. Chiral structures also give rise to unique chiroptical effects when interacting with polarized light. These properties are fundamental in biomolecular systems, and chiroptical spectroscopy is often used for their characterization. The aim of this work is to introduce chirality into inorganic nanosystems, in order to add an interesting degree of complexity and unravel new effects. Two different approaches for induction of chiral phenomena in inorganic nanocrystals are presented. In the first type of systems, chiral molecules are used to indcue chiroptical effects in the electronic transitions of achiral nanocrystals. This effect is interesting for fundamental studies of exciton/plasmon- molecular level interaction. However, it is generally very weak. More recently, we introduced the concept of enantioselective synthesis of intrinsically chiral inorganic nanocrystals, which leads to more pronounced effects. Many inorganic materials such as quartz, mercury sulfide and tellurium crystallize in chiral space groups with a chiral lattice. Biomolecules can be used to induce enantioselectivity in the nucleation and growth of nanoscrytals of these materials. For the case of tellurium, we show that crystal growth in the presence of the small peptide, glutathione, results in nanocrystals where the atomic scale lattice chirality translates to the overall shape chirality on a 100 nm scale. This is a unique example for a colloidal chemistry approach for self assembling inorganic nanocrystals, which exhibit chirality at two size hierarchies. These systems may be useful for applications in metamtaerials fabrication, asymmetric catalysis, sensing and optical devices. On a more fundamental level, these are excellent model systems for studies of chiral crystallization and separation, and the interaction of chiral biomolecules with chiral crystals. The possible role of chiral inorganic crystals and surfaces in the evolution of biomolecular homochirality has been considered by many researchers. Here it is demonstrated that the opposite effect, of biomoleucles affecting chiral inorganic crystallization, is also intriguing.

 

[317] UTILIZATION OF SELF-ASSEMBLED SHORT PEPTIDES NANOSTRUCTURES

 

Lihi Adler-Abramovich1

1 School of Dental Medicine; and the Department of Molecular Microbiology and Biotechnology

Utilization of Self-Assembled Short Peptides Nanostructures
Lihi Adler-Abramovich
Department of Oral Biology, The Goldschleger School of Dental Medicine, and the Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel.

[email protected]

Organic and inorganic self-assembled tubular nanostructures were suggested to have key potential in nanotechnological devices and applications. Several studies have shown the possible use of bionanometric material for applications ranging from molecular electronic to drug delivery. Short peptide motifs can efficiently self-assembles into discrete, well-ordered nanostructures.
In the current research, using different microscopy and spectroscopy tools, we describe a remarkable thermal and chemical stability of the aromatic-dipeptide-nanostructures [ADNS]. Furthermore, we studied the peptide nanotubes and nano-spheres mechanical properties and found that the peptide nanospheres have high Young’s modulus of up to 275 GPa, which places these peptide nano-assemblies among the stiffest bio-inspired materials presently known.
A limiting factor in the utilization of the ADNS system was the ability to spatially control the assembly process. Various methodologies were developed for the horizontal and vertical alignment of the ADNS and for their patterning. We used the inkjet technology for the application of ADNS on non-biological surfaces. Additionally, vapor-deposition technique was used to form vertically aligned nanotubes arrays that were later utilized for the formation of super-hydrophobic surface, sensitive sensors and ultracapacitors for energy storage applications.
In summary, the remarkable physical properties and the ability to control the assembly of the ADNS suggests their application in conventional microelectronic and microelectromechanics processes, as well as fabrication into functional nanotechnological devices.

 

[321] SYNTHESIS AND PROPERTIES OF NANOCRYSTALLINE Π-SNS – A NEW CUBIC PHASE OF TIN SULPHIDE

 

Ran Eitan Abutbul1, Elad Segev1, Leila Zeiri2, Vladimir Yazrasky1, Guy Makov3, Yuval Golan4

1 Ben-Gurion University of the Negev; Ilse Katz Institute for Nanoscale Science and Technology
2 Ilse Katz Institute for Nanoscale Science and Technology; Chemistry Department
3 Department of Materials Engineering; Ilse Katz Institute for Nanoscale Science and Technology
4 Ben Gurion University of Negev; Marcus Family Campus

Synthesis and Properties of Nanocrystalline π-SnS – A New Cubic Phase of Tin Sulphide

Ran E. Abutbul†‡, Elad Segev‡, Leila Zeiri‡#, Vladimir Ezersky‡, Guy Makov†‡ and Yuval Golan†‡
†Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
‡Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
#Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel

We report on the synthesis of the newly discovered cubic phase of tin sulfide π-SnS and compare its properties to the well-known phase of tin sulfide, -SnS. Shape control was achieved by variation of synthesis parameters, resulting in cubic, rhombic dodecahedral and tetrahedral shapes of the π-SnS nanoparticles. X-ray diffraction provided authentication of the proposed model and refined determination of the lattice parameter a=11.595 Å. Raman spectroscopy showed substantial shift towards higher energies and peak splitting for π-SnS. Optical absorption spectroscopy indicated an indirect band gap of 1.53 eV, in good agreement with density functional theory (DFT) calculations indicating a band gap greater than that of -SnS. DFT total energy calculations show that the π-SnS phase is energetically similar to α-SnS, and significantly more stable than the hypothetical ideal rocksalt structure of SnS.

 

[324] SYNTHESIS AND PROPERTIES OF NANOCRYSTALLINE Π-SNSE – A NEW CUBIC PHASE OF TIN SELENIDE

 

Ran Eitan Abutbul1, Elad Segev1, Leila Zeiri2, Vladimir Yazrasky1, Guy Makov3, Yuval Golan4

1 Ben-Gurion University of the Negev; Ilse Katz Institute for Nanoscale Science and Technology
2 Ilse Katz Institute for Nanoscale Science and Technology; Chemistry Department
3 Department of Materials Engineering; Ilse Katz Institute for Nanoscale Science and Technology
4 Ben Gurion University of Negev; Marcus Family Campus

Synthesis and Properties of Nanocrystalline π-SnSe – a new cubic phase of Tin Selenide

Ran E. Abutbul†‡, Elad Segev‡, Leila Zeiri‡#, Vladimir Ezersky‡, Guy Makov†‡ and Yuval Golan†‡
†Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
‡Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
#Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel

We report on a new binary phase in the tin mono-selenide system, Pi-SnSe, which was obtained as cube shaped nanoparticles. The structure and atomic positions was deduced using X-ray diffraction and Rietveld refinement (a0 = 11.939Å, No. 198), and showed a structure which is analogous to the recently reported cubic phase of SnS (a0 = 11.595Å, No. 198). The new cubic SnSe phase was further characterized by Raman and optical absorption spectroscopies. The optical band gap was assessed to be indirect, with Eg=1.28eV (in the near infrared), compared to Eg=0.9eV (indirect) and 1.3eV (direct) eV for the conventional orthorhombic phase of SnSe. DFT calculation has been applied in order to validate the phase stability.

 

[326] CHEMICAL BATH DEPOSITION OF NANO COLUMNAR THIN FILMS OF PBSE

 

Tzvi Templeman1, Nizan Maman2, Amir Tal3, sucheta sengupta4, Alexander Rabkin5, Michael Shandalov6, Iris Visoly-Fisher2, Gabby Sarusi3, Yuval Golan4

1 Ben-Gurion University ; Department of Material Engineering
2 Swiss Institute for Dryland Environmental and Energy Research; Swiss Institute for Dryland Environmental and Energy Research
3 Ilse Katz Institute for Nano-Scale Science and Technology; Department of Electrooptics Engineering
4 Ben Gurion University of Negev; Marcus Family Campus
5 Ilse Katz Institute for Nano-Scale Science and Technology; Ilse Katz Institute for Nano-Scale Science and Technology
6 Department of Physics; Department of Physics

Chemical Bath Deposition of Nano Columnar Thin Films of PbSe
Tzvi Templeman1,2, Nitzan Maman4, Amir Tal1,3, Sucheta Sengupta1, Alexander Rabkin1, Michael Shandalov5, Iris Visoly-Fisher1,4, Gabby Sarusi1,3 and Yuval Golan1,2
1Ilse Katz Institute for Nano-scale Science and Technology, Ben Gurion University of the Negev, Israel
2Department of Materials Engineering, Ben Gurion University of the Negev, Israel
3Department of ElectroOptics Engineering, Ben Gurion University of the Negev, Israel
4Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Israel
5Department of Physics, Nuclear Research Center Negev, P.O. Box 9001 Beer Sheva, Israel

The present study describes the morphology and growth kinetics of nano-columnar PbSe films grown on GaAs(100) substrates using chemical bath deposition (CBD). Although columnar film growth is well established in chemical and physical vapor deposition, this is not the case in CBD, where the two main mechanisms which describe film growth are the ion-by-ion (IBI) and cluster growth mechanisms. In this work we present a previously unreported mechanism in CBD which leads to columnar growth.
Films were investigated using XRD, HRSEM and TEM. The initial nucleation density is controlled by bath parameters, specifically temperature and complex/cation ratio. Growth is interrupted in lateral x-y dimensions and enhanced along z, resulting in columnar morphology. Well-defined orientation relations were established with the substrate, and interestingly, neighboring columns were found to be in alternating twinning relations. A clear transition to IBI occurs as growth proceeds and complex/cation ratio increases, a transition which can be prevented by replenishing bath concentrations.
Current-sensing AFM was used to measure the transport properties and lateral electronic homogeneity. The nano-column boundaries showed insulating behavior while grain interior shows good conduction along the z direction, which is advantageous for the use of these films as SWIR absorbers in upconversion night vision devices.

 

[335] CHEMICAL BATH DEPOSITED PBS(TH) THIN FILMS FOR INFRARED DETECTION

 

Nitzan Maman1

1 Bgu; Bgu

Chemical Bath Deposited PbS(Th) Thin Films for Infrared Detection
Nitzan Maman1 , Tzvi Templeman2,3, Amir Tal2,4, Michael Shandalov5, Sucheta Sengupta2, Alexander Rabkin2, Yuval Golan2,3 , Gabby Sarusi2,4 and Iris Visoly-Fisher1,2
1Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Israel
2Ilse Katz Institute for Nano-scale Science and Technology, Ben Gurion University of the Negev, Israel
3Department of Materials Engineering, Ben Gurion University of the Negev, Israel,
4Department of ElectroOptics Engineering, Ben Gurion University of the Negev, Israel
5Department of Physics, Nuclear Research Center Negev, P.O. Box 9001 Beer Sheva, Israel

The electronic and optical properties of PbS(Th) films with nano-spherical morphology deposited on GaAs(100) substrates were studied in order to determine their potential use as SWIR absorber material for upconversion night vision devices. The films were grown by chemical bath deposition during which small concentrations of Th+4 cations were incorporated, The films demonstrated quantum confinement effects, in which the band gap increases with Th at%.
FTIR transmission measurements showed a strong absorption band at 1.8 µm for films containing ~8 at% Th. Several absorption states in the forbidden gap were monitored as a function of post-deposition thermal treatment parameters such as temperature, duration and atmosphere.
Photoconduction measurements were performed on these films in the dark and under SWIR illumination ( nm, 5mW) as a function of film thickness and different thermal treatments. The resistivity of the films was found to decrease by more than 50% under SWIR illumination compared to dark resistivity.

 

[341] HYBRID LEAD SULFIDE QUANTUM DOT- LEAD HALIDE PEROVSKITE BASED SOLAR CELLS

 

Daniel Amgar1

1 The Hebrew University of Jerusalem; The Hebrew University of Jerusalem

Hybrid Lead Sulfide Quantum Dot- Lead Halide Perovskite Based
Solar Cells
Daniel Amgar, Lioz Etgar
The Institute of Chemistry, Casalli Center for applied chemistry
The Hebrew University of Jerusalem

The research concentrates on the development of novel solar cells. The motivation is creating renewable energy from the sun as an endless energy source by fabricating high efficiency and low cost solar cells. Photovoltaic cells are made of a variety of materials and architectures and this work will be involved with third generation solar cells, while working on hybrid perovskite nanoparticles – PbS quantum dots based solar cells. Perovskite has the chemical formula of ABX3 when A is a cation, B is a metallic bivalent cation and X is a halide. The use of all kinds of perovskite for photovoltaic applications derives from its great advantages as a light absorbing material what can improve cells performance. The perovskite is characterized with a band gap suitable for the visible region of the solar spectrum, low bonding energies, high charge carrier mobilities and large diffusion lengths. PbS quantum dots have the ability to absorb NIR photons through size-tuning of their bandgap and show potential for multiple exciton generation. In addition, both materials allow affordable and easy solution process ability.
The main goal is combining both materials while using the special properties of the perovskite and the QDs in order to utilize the energy of photons from all across the solar spectrum as much as possible and as a result, developing hybrid cells integrating these two materials.

 

[342] WS2 NANOTUBES AS TEMPLATES FOR FUSION OF METALLIC NANOPARTICLES

 

Priyadarshi Ranjan1, Ronit Popovitz Biro2, Ifat Kaplan-Ashiri1, Michal Lahav3, Reshef Tenne4, Milko E. van der Boom3

1 Weizmann Institute of Science; 234 Hertzl
2 Department of Chemical Research Support; Weizmann Institute of Science
3 Weizmann Institute of Science; 234 Hertzl St.
4 Department of Materials and Interfaces; Weizmann Institute of Science

WS2 nanotubes as templates for fusion of metallic nanoparticles
Priyadarshi Ranjanϯ,§, Ronit Popovitz-BiroƮ, Ifat Kaplan-AshiriƮ, Michal Lahavϯ,
Reshef Tenne§, and Milko E. van der Boomϯ

ϯDepartment of Organic Chemistry, §Department of Materials and Interfaces, ƮDepartment of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel 7610001

Nanotubes of WS2 (INT-WS2) have been uniformly decorated by gold nanoparticles of 5 nm diameter, silver nanoparticles of 17 nm diameter, and palladium nanoparticles of 2 nm diameter. This process is likely driven by lattice matching of these crystalline materials. The stepwise decorations of INT-WS2 by the metallic nanoparticles can be used to tune the optical properties of the ensembles. Remarkably, thermolysis of our hybrid ensembles results in the fusion of the particles on the surface of INT-WS2. Fusion of the gold nanoparticles results in the formation of a single nanodecahedron particle on the nanotube. Follow-up electron microscopy studies provided fundamental insights into the nanoparticle fusion processes.

 

[345] VT-STM STUDIES OF SUPERPARAMAGNETISM AND THE VERWEY TRANSITION IN FE3O4 NANOCRYSTALS

 

Amir Hevroni1, Gil Markovich2

1 School of Chemistry; Tel Aviv University
2 School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences; Tel-Aviv University

In the first project, the magnetization dynamics of individual magnetite nanocrystals was probed by variable temperature magne¬toresistive scanning tunneling microscopy, in which a magnetoresistive junction is formed between the substrate and the magnetic par¬ticle under study. When the temperature was tuned close to the magnetization blocking of a superparamagnetic particle, the slow magnetization switching of the particle caused fluctuations in the tunnel current passing through the particle, which appeared as telegraph noise in current vs. time measurements. Analysis of the current fluctuations yielded estimates for the small local magnetic field sensed by the particle, its magnetic anisotropy energy, and a low limit for its spin-polarization degree. For one of the particles, the spin-polarization appeared to be as high as 90%.
In the second project, the temperature evolution of the density of states in, co-precipitation-synthesized, ~10 nm magnetite nanocrystals around magnetite’s metal-insulator transition temperature (Verwey transition) was probed using variable temperature scanning tunneling spectroscopy. The transition was observed as a significant change in the electronic structure around the Fermi level, with an apparent band-gap of ~140-240 meV appearing below the transition temperature, and a pseudo-gap of ~75±10 meV appearing above it. Since the particles studied are only few unit cells in size, it is quite a surprise that such a sharp transition was observed in view of the significance of long-range charge ordering in the low-temperature phase. The transition temperature was invariably observed around 101±2K for different nanocrystals, as opposed to 123K typically found in stoichiometric bulk crystals. This suggests that the lowering of the transition temperature is an intrinsic finite size effect, probably due to the presence of the surface. The transition was also shown to be hysteretic with supercooling of 5-8K.

 

[348] CARBON NANOTUBE – QUANTUM ROD LIGHT INDUCED ENERGY TRANSDUCTION FOR RETINAL STIMULATION

 

Gur Lubin1

1 Tel Aviv University; Tel Aviv University Center for Nanoscience and Nanotechnology

Carbon nanotube – quantum rod light induced energy transduction for retinal stimulation
Gur Lubin 1,2, David Rand 1,2, Lilach Bareket Keren 1,2, Jacob Ben-Dov 1,2, Nir Waiskopf 3,4, Dorit Raz Prag1,2, Soumyendu Roy 1,2, Moshe David Pur 1,2, Uri Banin 3,4, Ori Cheshnovski 1,5, Yael Hanein 1,2
1Tel-Aviv University Center for Nanosciecne and Nanotechnology, Tel Aviv, Israel
2School of Electrical Engineering, Tel Aviv University, Israel
3Institute of Chemistry, The Hebrew University of Jerusalem, Israel
4Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Israel
5School of Chemistry, Tel Aviv University, Israel

Retinal degeneration is a common cause of age and non-age related blindness. Electrical stimulation of a degenerated retina has the capacity to elicit visual responses in the brain, and restore vision. Here we report on light induced activation of a blind chick embryo retina in-vitro using a novel bio-mimetic carbon nanotube (CNT) – semiconductor quantum rod (QR) based platform. This result highlights the CNT-QR nanocomposites’ potential to enable high resolution, wire free activation of neurons, addressing the main setbacks of today’s state of the art retinal prosthesis technology. To gain a better understanding of the underlying mechanism of the light harvesting in these composite films, we present an optical investigation into the light response of various QR – metal hybrids. Fluorescence quenching, indicated by a shortening of the QR fluorescence lifetime, together with photo-electrical measurements, point to an efficient energy harvesting mechanism in the CNT-QR hybrids. Combining this mechanism with the excellent performance of CNT mesh electrodes for electrical interface with neurons, we were able to achieve light induced neuronal activation in ambient light intensities.

Bareket, Lilach, et al. “Semiconductor Nanorod–Carbon Nanotube Biomimetic Films for Wire-Free Photostimulation of Blind Retinas.” Nano letters 14.11 (2014): 6685-6692.

 

[349] THE EFFECT OF CITRATE AS A CO-COMPLEXANT DURING CHEMICAL BATH DEPOSITION OF PBS THIN FILMS

 

Maayan Perez1, sucheta sengupta2, Yuval Golan2

1 Ben Gurion University; Iki
2 Ben Gurion University of Negev; Marcus Family Campus

The effect of citrate as a co-complexant during chemical bath deposition of PbS thin films
Maayan Pereza, Sucheta Senguptaa and Yuval Golana
a. Department of Materials Engineering, and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.

Tri sodium citrate (citrate) has been commonly used as a co-complexing agent during chemical bath deposition to improve film quality and control grain size, yet its precise role has not been elucidated to date. In this study, we have focused on the role of citrate in chemically deposited PbS thin films. Citrate effectively complexes the lead cation in solution, thereby decreasing growth rate and inducing growth in the cluster mechanism. This was monitored in real time using laser light-scattering and UV-Vis absorption spectroscopy which quantitatively confirmed the retarded PbS formation in the cluster mechanism in the presence of citrate. Nanocrystalline PbS films formed in presence of citrate show quantum confinement effects with blue shifted optical properties compared to the bulk, adding an important path for controlling film properties towards future infrared optoelectronic applications.

 

[354] CONDUCTIVE COPPER COMPLEX INKJET INK WITH SELF REDUCTION MECHANISM FOR FLEXIBLE ELECTRONICS

 

Yousef Farraj1, Shlomo Magdassi2

1 Casali Center for Applied Chemistry; Chemistry
2 The Hebrew University of Jerusalem; Chemistry

Conductive copper complex inkjet ink with self reduction mechanism
for flexible electronics

Yousef Farraj, Shlomo Magdassi
Casali Center for Applied Chemistry, Institute of Chemistry and Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

In the past decade, the fabrication of low-cost flexible electronics by printing has gained a lot of interest in devices such as circuit boards, RFID tags, touch screens and flexible displays. In particular, inkjet printing of metals for conductive patterns is a promising approach for producing low cost electronic devices on flexible substrates. Several reports on printing metallic nanoparticles inks, usually silver, at low temperature, were reported recently. However, their high cost limits the fabrication of low cost plastic devices and therefore, there is an unmet need to find a replacement inks based on low cost metals. Among metals, copper is the most promising candidate, having the second lowest resistivity, and its cost is 90 times lower than that of silver. Nevertheless, the main challenge with copper-based inks is to prevent the oxidation of the copper nanoparticles before and after printing.
Here we describe the formation and utilization of a metal ink based on copper complexes that undergoes decomposition and conversion to copper nanoparticles at low temperatures (below 150 °C). Therefore this ink enables printing conductors on heat sensitive plastic substrates such as PET and PEN. The conversion to copper can be done either by conventional heating or by other methods as flash sintering, and lasers. The ink is stable in ambient conditions for prolonged periods, without any deterioration of its functionality, as compared to what is usually encountered in nanoparticles based inks, such as aggregation and formation of copper oxide.

 

[357] BUFFER LAYER ASSISTED GROWTH OF METAL NANOPARTICLES IN TITANIA THIN FILMS FOR PHOTOCATALYSIS APPLICATIONS

 

Liat Zilberberg1, Serge Mitlin2, Shankar Harisingh3, Micha Asscher1

1 Faculty of Science; The Institute of Chemistry
2 Faculty of Science ; The Institute of Chemistry
3 Faculty of Science ; Chemistry

Buffer Layer Assisted Growth of metal Nanoparticles in Titania Thin Films
for Photocatalysis Applications
L. Zilberberg, S. Mitlin, H. Shankar and M. Asscher
Institute of Chemistry, Edmund J. Safra Campus,
The Hebrew University of Jerusalem, Jerusalem 91904, Israel

Developing materials with improved photocatalytic activity is important for light energy conversion and storage within chemical bonds. Here we present a new type of hybrid films of silver nanoparticles (AgNPs) embedded within TiOx (x≤2) to approach this goal, introducing visible light absorption via surface-plasmon excitation of the AgNPs. Silver nanoparticles were prepared by an ultra-high vacuum (UHV) based Buffer Layer Assisted Growth method. The titania films as a substrate and protective layers were grown by the Reactive Layer Assisted Deposition (RLAD) technique, in both cases amorphous solid water (ASW) was the buffer material. The thin titania films and the AgNPs were ex-situ characterized by UV-VIS, micro-Raman, XRD, XPS, SEM and TEM techniques. The titania protective layers on top of the silver particles were found to introduce a dielectric environment for the AgNPs, leading to a significant red-shift of their plasmon resonance from 460 to 530 nm, in addition to avoiding oxidation of the small nanoparticles. Photo-induced activity of these hybrid films has been tested following the degradation of methylene blue (MB) in aqueous solution under both UV and visible pulsed laser irradiation. Preliminary results have shown photo-catalytic activity of the RLAD titania film with only marginal influence due to the presence of the AgNPs. However, it seems that the irradiation causes partial degradation of the AgNPs and lead to doping of the TiO2, which yields absorption tail in the visible region. In order to observe the plasmon enhancement we try to get energy overlapping between the plasmon and the oxide. For this purpose hybrid materials containing aluminum nano particles were prepared and examined.

 

[361] HIERARCHICALLY-STRUCTURED NANOCOMPOSITE FILMS ASSEMBLED ON TOPOGRAPHICALLY PATTERNED SUBSTRATES

 

Elisheva Michman1, Meirav Oded1, Ernesto Joselevich2, Mark Schvartzman3, Roy Shenhar4

1 Institute of Chemistry; The Hebrew University of Jerusalem
2 Department of Materials and Interfaces; Weizmann Institute of Science
3 Department of Materials Engineering; Ben-Gurion University of the Negev
4 The Hebrew University of Jerusalem; Givat Ram

Hierarchically-structured nanocomposite films assembled on topographically patterned substrates

Elisheva Michman1, Meirav Oded1, Ernesto Joselevich2, Mark Schvartzman3 and Roy Shenhar1
1Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
2Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
3Department of Materials Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel

Co-assembly of block copolymers and nanoparticles in composite thin films has become a leading bottom-up method of nanoparticle organization for functional devices. The effects of nanoparticle size, surface chemistry, and filling fraction on the location of nanoparticles within block copolymer domains is the subject of considerable ongoing investigation. However, the nanocomposite films in most of these studies lack the long-range order required for various technological applications. Whereas directed self-assembly using lithographically-defined substrate patterns has been shown as a powerful approach for aligning block copolymer domains along macroscopic coordinates, the directed self-assembly of nanocomposite films is so far rather unexplored.
We studied the assembly of thin films of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) block copolymers with and without gold nanoparticles on topographically patterned silicon substrates. The patterned substrates, featuring stripes of different widths and separation distances, were obtained by nanoimprint lithography. Interestingly, different local morphologies of the block copolymer were observed on the stripes and inside the gaps. Even more elaborate structures were observed in nanocomposite films, where the nanoparticle filling fraction has been found to be a determining factor in the order and morphology of the film. The poster will present the different morphologies observed and will explore possible explanations for their occurrence.

Example of a hierarchical nanocomposite morphology obtained on a topographically patterned substrate.

 

[362] CHEMICAL BATH DEPOSITION AND CHEMICAL EPITAXY OF CADMIUM SULFIDE THIN FILMS ON GAAS SUBSTRATE

 

Ofir Friedman1, Yuval Golan2

1 Ben-Gurion University of the Negev; Marcus Family Campus
2 Ben Gurion University of Negev; Marcus Family Campus

Chemical Bath Deposition and Chemical Epitaxy of Cadmium Sulfide Thin Films on GaAs Substrate

Ofir Friedman and Yuval Golan
Department of Materials Engineering, and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel

Chemical bath deposition (CBD) from solution offers a simple and cost-effective route for the fabrication of high quality semiconductor thin films, without the need for high deposition temperatures, stringent vacuum or plasma generators. Chemical epitaxy is particularly advantageous for obtaining monocrystalline thin films with well-defined orientation relations with the monocrystalline substrate. Notably, understanding the chemical and physical mechanisms governing chemical epitaxy can allow us to predict and control the orientation of thin films.
Cadmium sulfide (CdS) is a II-VI semiconductor with a wide and direct band gap of 2.42 eV. In this work, we have studied the microstructure and morphology of CdS films chemically deposited on GaAs(100). The deposition of CdS on GaAs was found to be strongly influenced by several parameters, including the order of reagents addition, reagent concentrations, pH, time and temperature. The CdS films grown on GaAs(100) showed a ; orientation relationship, providing the first reported evidence for chemical epitaxy in CBD CdS on GaAs(100).

 

[364] PRINTING OF COPPER PATTERNS ON 2D AND 3D OBJECTS YIELDING 50% BULK CONDUCTIVITY BY USING A SELF-REDUCING PRECURSOR

 

Yitzchak (Isaac) Rosen1, Shlomo Magdassi2

1 Casali Center for Applied Chemistry; Center for Nanoscience and Nanotechnology
2 Casali Center of Applied Chemistry; The Hebrew University of Jerusalem

Printing of copper patterns on 2D and 3D Objects Yielding 50% Bulk Conductivity by Using a Self-Reducing Precursor

Yitzchak (Isaac) Rosen and Prof. Shlomo Magdassi (HUJI)

Fabrication of devices by printing conductive interconnections on plastic substrates is of growing research interest. Therefore, several approaches for the sintering of metallic nanoparticles (NP), mainly silver were recently developed. However, the high cost of silver limits commercial use and therefore inks with other metals, such as copper, are required. Inks containing copper NPs suffer from stability problems, as the NPs are quickly oxidised, and so lose their conductivity. Therefore, there is an unmet need for a copper ink with a low sintering temperature.
Two concepts for forming copper conductive patterns were examined. The first approach is based on using a new dispersion ink that contains nano and sub-micron copper salt particles which are stable to oxidation. This ink was used as a Metal Organic Decomposition ink which is printed and then heated to induce thermal decomposition. During decomposition, the organic matter is broken down to volatile species while reducing the copper, thus leaving a Cu° pattern.
Another approach is based on the use of copper precursors in a transfer printing process that results in 50% bulk copper conductivity. Two steps are involved in the process. In the first step, the mirror image of a desired pattern is printed with the ink on a “donor substrate”. In the second step, this pattern decomposes by heating under N2 gas, and copper is transferred to a close by “acceptor substrate” through the gas phase. This approach can be used to pattern 2D substrates and performed onto 3D objects with several advantages; it is non-contact, eco-friendly, low cost, and a dense layer of copper is obtained leading to low resistivity.

“Printing of Self-Reducing Copper Precursor Yielding 50% Bulk Conductivity on 2D and 3D Objects” Advanced Materials Interface, 2015.

 

[365] LARGE SCALE COLLOIDAL PRODUCTION OF ULTRATHIN TWO-DIMENSIONAL (2D) BI2SE3 TOPOLOGICAL INSULATORS AND ITS DOPED ANALOGUES

 

pradipta sankar maiti1

1 Ben-Gurion University of the Negev; Department of Chemistry

Title
Large Scale colloidal production of ultrathin two-dimensional (2D) Bi2Se3 topological insulators and its doped analogues
Abstract
Ultrathin 2D Bi2Se3 nanostructures with few quintuple layers (QL) have emerged new exciting material due its topological insulator properties. The surface conductivity of these exotic materials is highly influenced by their layer thickness. In contrast to tradition MBE techniques, these structures can be prepared in solution phase in large scale with controlled and uniform thickness (~5 -10 QL) that is small compared to their lateral dimensions. Furthermore, doping these topological insulators with materials like Mn2+, Sb+3 can alter their chemical potential which also provides us additional degree of freedom which can be used to tune their properties by varying their composition. These doped-Bi2Se3 nanostructures can open new possibilities in device engineering in the field of spintronics and low-energy electronics.
Here, we are going present the colloidal synthesis of the ultrathin 2D Bi2Se3 nanosheets as well as their physiochemical properties. We will be showing the effect of magnetic and non-magnetic doping on the shape, size, optical and magnetic properties of these 2D nanostructures. Structural, compositional and optical characterizations are going to be presented using SEM, TEM, UV-visible absorption, powder X-diffraction (PXRD), XPS and SQUID measurements.

 

[366] HIGH PERFORMANCE 3D PRINTING OF HYDROGELS BY WATER-DISPERSIBLE PHOTO-INITIATOR NANOPARTICLES

 

Amol Pawar1, Gabriel Saada1, ido cooperstein2, Liraz Larush1, Shlomo Magdassi1

1 Casali Center of Applied Chemistry; The Hebrew University of Jerusalem
2 The Hebrew University of Jerusalem; Casali Institute for Applied Chemistry

Title: High performance 3D printing of hydrogels by water-dispersible photo-initiator nanoparticles

Authors: Amol A Pawar, Gabriel Saada, Ido Cooperstein, Liraz Larush and Shlomo Magdassi
Affiliation: Casali Center for Applied Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel

Application of 3D printing using photo-polymerization based processes for making hydrogels and devices for tissue engineering applications is restricted by the lack of water soluble photo-initiators. A new approach to enable rapid 3D printing of hydrogels in aqueous solutions is presented, based on UV curable inks containing nanoparticles of highly efficient, but water insoluble photoinitiator. TPO (Ethyl-2,4,6 trimethylbenzoyl-phenyl phosphinate) is a water-insoluble, crystalline photo-initiator used to facilitate photo-polymerization through UV curing. The present work aims to prepare amorphous, water dispersible TPO nanoparticles by rapid conversion of volatile microemulsions droplets. The extinction coefficient of the new water dispersible nanoparticles of TPO is more than 300 times larger than the best commercially available and mostly used water soluble photoinitiator. The TPO nanoparticles absorbs significantly in the range of 385 – 420 nm, making them suitable for use in commercially available, low cost LED based digital light processing 3D printers. The polymerization rate at this range is very fast, and enables 3D printing that otherwise is impossible to perform without adding solvents. Such water dispersible photo-initiator nanoparticles opens many opportunities in enabling rapid 3D printing of structures prepared in aqueous solutions, while bringing environmental advantages by using low-energy curing systems and by avoiding the need for solvents.
Keywords: 3D printing; hydrogels; photoinitiator; TPO; UV curing

 

[371] AN ULTRASENSITIVE METHOD FOR PROTEIN AND DNA DETECTION AT THE SINGLE MOLECULE LEVEL

 

Haya Dachlika1

1 Hebrew University of Jerusalem; Hebrew University of Jerusalem

An ultrasensitive method for protein and DNA detection at the single molecule level
One of the central challenges of humanity is the prediction, prevention, and early detection of diseases. A possible path to meet this challenge is the development of highly sensitive methods for early detection of disease biomarkers and proteins. The proposed method is based on conjugation of the ligands to metal nanoparticles (NP) and binding of the conjugated complex to the macromolecule. Later, the formed structures will be characterized using electron microscopy (EM) that enables ultrasensitive detection of the NP dimers.
The first and simple model system was based on NP-DNA conjugates. In this model system, gold nanoparticles (GNP) with different sizes, conjugated to two different DNA oligonucleotides. The NP-DNA conjugates were connected through hybridization by a third DNA oligonucleotide that is representing the target macromolecule, and dimers were formed. The dimers are the only NPs in the sample solution that are connected to the third DNA. Thus it is possible to identify and quantify them even at low abundance by EM. As a protein model system we used ASPP2 protein that has known separated binding sites for various proteins and peptides. Here, two different peptides were conjugated to GNPs with different sizes. The ASPP2 protein was then bound to the GNP-peptide conjugates and GNP dimers were formed. The formed structures, in which each biomarker is flanked by two easily recognizable NPs (a dimer) will be detected and characterized using EM.

 

[377] CREATION OF HIGH DENSITY ENSEMBLES OF NITROGEN-VACANCY CENTERS IN NITROGEN-RICH TYPE IB NANODIAMONDS

 

Jui-Hung Hsu1

1 Department of Materials and Opto-Electronic Science; National Sun Yat-Sen University

We present the fabrication and analysis of fluorescent nano-diamonds (FNDs) containing high density ensembles of negatively-charged nitrogen vacancy (NV-) color centers in diamond nanoparticles of various sizes (10–100 nm) using nitrogen-rich type Ib diamond powders as the starting material. The nanodiamonds were prepared by ball milling of microdiamonds, in which the density of neutral and atomically dispersed nitrogen atoms ([N0]) was measured by diffuse reflectance infrared Fourier transform spectroscopy. A systematic measurement of the fluorescence intensities and lifetimes of the crushed monocrystalline diamonds as a function of [N0] indicated that [NV-] increases nearly linearly with [N0] at 100–200 ppm. The trend, however, failed to continue for nanodiamonds with higher [N0] (up to 390 ppm) but poorer crystallinity. We attribute the result to a combined effect of fluorescence quenching as well as the lower conversion efficiency of vacancies to NV- due to the presence of more impurities and defects in these as-grown diamond crystallites. We demonstrate that it is possible to improve the brightness of FNDs with the [N0] increasing from 100 ppm to 200 ppm for crushed monocrystalline diamonds. Our results indicate that through careful control of the radiation damage conditions and proper choice of the diamond materials, increase of [NV-] above 10 ppm in 10 nm FND particles is practical.

 

[383] NANOPOROUS SINGLE CRYSTALS OF GOLD

 

Maria Koifman1, Leonid Bloch2, Manfred Burghammer3, Yaron Kauffmann2, Alexander Katsman2, Boaz Pokroy1

1 Department of Materials Science and Engineering, Technion − Israel Institute of Technology; Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology
2 Department of Materials Science and Engineering, Technion − Israel Institute of Technology; Nr
3 European Synchrotron Radiation Facility; Nr

Single crystals in nature often demonstrate fascinating intricate porous morphologies rather than classical faceted surfaces. We are growing such crystals, drawing inspiration from biogenic porous single crystals. Here we show that nanoporous single crystals of gold can be grown with no need for any elaborate fabrication steps. These crystals are found to grow following solidification of a eutectic composition melt that forms as a result of the dewetting of nanometric thin films. We also present a kinetic model that shows how this nano-porous single-crystalline structure can be obtained, and which allows the potential size of the porous single crystal to be predicted. Retaining their single-crystalline nature is due to the fact that the full crystallization process is faster than the average period between two subsequent nucleation events. Our findings clearly demonstrate that it is possible to form singe crystalline nano porous metal crystals in a controlled manner. We also show that nanoporous single crystal prepared by eutectic composition demonstrate superior thermal stability as compared to their counterpart nanoporous gold prepared by dealloying, which is essential for catalysis.

 

[392] SOFT-SUBSTRATE-RIGID-FEATURE (SSRF) NANOIMPRINT LITHOGRAPHY

 

Liran Menahem1, Mark Schvartzman2

1 Department of Materials Engineering, Ilse Katz Institute for Nanoscale Science and Technology.; P.O. Box 653, Beer-Sheva 84105, Israel.
2 Department of Materials Engineering; Ben-Gurion University of the Negev

SOFT-SUBSTRATE-RIGID-FEATURE (SSRF) NANOIMPRINT LITHOGRAPHY
Liran Menahem, Dr. Mark Schvartzman
Department of Materials Engineering, Ilse Katz Institute for Nanoscale Science and Technology.
Ben-Gurion University of the Negev.
P.O. Box 653, Beer-Sheva 84105, Israel.

Two existing approaches of Nano Imprint Lithography (NIL) are defined by the mold material. In hard NIL, molds are made of rigid materials, such as Silicon or Quartz. These molds offer nanometer resolution and superior pattern fidelity, .however, they are extremely sensitive to surface contamination and defects. Alternatively, soft molds are made of cast elastomers (Poly(Dimethylsiloxane) – PDMS). They offer highly conformal contact and low contaminant sensitivity, and can imprint curved surfaces, however, their compressibility makes the pattern features deform, buckle, or collapse, resulting in pattern distortion and limited resolution
Here, we introduce a novel hybrid Soft-Substrate-Rigid-Feature (SSRF) nanoimprint mold based on soft substrate with rigid relief features. It combines the advantages of each of the traditional molding approaches, and at the same time overcomes their drawbacks: (i) High pattern fidelity and small feature size as offered by hard molds; and (ii) low sensitivity to defects and patterning curved substrates as offered by soft molds.
We produced SSRF molds by electron-beam lithography (EBL) of Hydrogen Silsesquioxane (HSQ) on a sacrificial substrate, and transferred the obtained HSQ features to PDMS substrates. Anti-adhesive coating usually used for hard Si molds was successfully applied on SSRF mold, and found to be essential for the mold durability. The molds were used for nano imprint of UV-curable resists. Using ultra-high resolution EBL we produced SSRF mold with sub-20 nm pattern. In summary, we have demonstrated an innovative concept of robust, high-quality, and cost-effective nanoimprint, which will open a pathway to numerous applications impossible up today.

Key Words: Electron Beam Lithography, High Resolution.

Additional suggested keywords: Nano Imprint, Soft lithography.

 

[396] TWEAKING ELECTROCHEMICAL PROPERTIES OF CARBON NANOTUBE BY SURFACE MODIFICATION

 

krishna kant1

1 Institute of Biochemistry, Food Science, and Nutrition; The Hebrew University of Jerusalem,

Tweaking electrochemical properties of carbon nanotube by surface modification
K.Kant1,2, M. Alsawat1, T. Altalhi1 and D. Losic1

1School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia
2Institute of Biochemistry, Food Science, and Nutrition Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel

Exceptional properties of carbon nanotubes (CNTs), including electrical conductivity, mechanical strength, smooth hydrophobic graphitic walls, electronic, thermal properties, have led to the development of membrane based separation technologies. Nano-porous alumina membranes (NPAM) is been used as template to fabricate CNTs membranes with controllable nanotube dimensions by catalyst-free CVD approach. In this work, we focused on the study of electrochemical properties of CNT/NPAM by the use of electrochemical impedance spectroscopy (EIS). The specific objectives were to explore the surface modifications of CNTs and their electrochemical properties which can be used as a strategy for electrophoretic and potential based separation of charged molecules. NPAM was prepared by a two-step anodization process using 0.3 M oxalic acid as electrolyte at 0°C. CNTs were fabricated inside the pores of the template of NPAM by catalyst-free CVD approach. The chemical modification of CNTs (Mo-CNTs) was performed by hydrogen peroxide (H2O2) treatment in order to introduce oxygen-containing group, mainly hydroxyl, in the inner surface of CNTs. The morphology and chemical composition of the prepared CNT and Mo-CNT membranes were characterized using scanning electron microscopy (SEM) transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrical properties were characterized by a four-point electrode impedance system in the frequency range from 1 Hz to 1MHz using various concentrations of NaCl electrolyte. The transport properties of CNT/NPAM and Mo-CNT/NPAM were characterized using two model molecules (uncharged and charged). Our results confirmed that simple chemical oxidation process of CNTs can be used to tune their conductivity and interfacial properties which can be used to control their transport and chemical selectivity characteristics.

 

[397] PROTEIN MAPPING ON ICE SURFACE BY USING QUANTUM DOTS

 

krishna kant1

1 Institute of Biochemistry, Food Science, and Nutrition; The Hebrew University of Jerusalem,

Protein mapping on Ice surface by using quantum dots
Krishna Kant and Ido Braslavsky

Institute of Biochemistry, Food Science, and Nutrition, Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel

Water and ice are two most abundant materials available on the earth and it’s been always in interest of human being to understand the exceptional properties of the ice/water interface. It is important for the microscopic study of macromolecules in field of biology and organic chemistry. Therefore the surface of ice has been investigated by use of various fluorescent techniques. The characterization of ice surface by fluorescent microscopy offers the possibility to examine the ice surface and protein binding efficiency under numerous conditions at high resolution. However, molecular level observation of ice crystal surfaces is very challenging. The short life time of fluorescent molecule and low brightness are major challenge to do imaging over the ice surface. The use of anti-fading agents make this process complicated and originality of the ice sample is been sacrificed. Herein we are proposing the use of hydrophilic CdTe quantum dots (2 nm) which can be easily tagged with the anti-freezing proteins and bind on the ice surface easily. The local heating of the quantum dots over the ice surface can be a problem when it been hit by laser beams. To overcome the problem, employing anti freezing protein (AFP) is useful which have properties to sustain the thermal hysteresis by +2 оC. These proteins have been evolved in a variety of cold adapted organisms such as fish, insects, bacteria, and plants. Antifreeze proteins are one class of the ice-binding proteins which have capability to control growth of ice-crystal. In this proposed research, a new approach for exploring the molecular activity of AFPs on ice surface will be developed to address open questions of protein interaction with ice surface and its arrangement over the ice crystal.

 

[398] SYNTHESIS OF AIR-STABLE COPPER PARTICLES WITH SILVER NANOSHELL BY TRANSMETALLATION METHOD

 

Anna Pajor-Swierzy1

1 The Hebrew University of Jerusalem; Casali Center of Applied Chemistry

Synthesis of air-stable copper particles with silver nanoshell by transmetallation method
Anna Pajor-Świerzy, Alexander Kamyshny, Shlomo Magdassi
Casali Center of Applied Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem, Israel

Currently, most conductive nanoinks for printing various electronic devices are based on silver nanoparticles (NPs). However, large-scale production of printed electronic devices requires low-cost inks, in which silver as a conductive functional material is replaced by much cheaper base metals. The most suitable metal is copper with conductivity of about 95% of that for silver. The specific challenge while utilizing copper particles is their oxidation at ambient conditions. The most effective approach to obtaining stable copper particles is coating them with a protective nanoshell of noble metals, i.e. formation of bimetallic core-shell particles (core@shell).
In this research, stable to oxidation Cu particles, were synthesized by formation of Ag nanoshell on their surface with the use of three-step process: (1) formation of dispersion of Cu particles from Cu(NO3¬)¬2¬ as a precursor and a reducing agent, sodium formaldehyde sulfoxylate, in the presence of a polymeric stabilizer, polyacrylic acid sodium salt; (2) removing an excess of reducing agent by washing the Cu dispersion with a solution of ascorbic acid; and (3) transmetallation (galvanic displacement) reaction between silver ammonia complex (AgNO¬3¬-NH¬3¬) and Cu atoms on the surface of Cu particles resulting in formation of Cu@Ag particles. The structure of the Cu@Ag NPs was analyzed and supported by UV-VIS spectra, X-ray Diffraction (XRD) and SEM electron mapping.
At the next stage, Cu@Ag particles were used for formulation of conductive inks. To optimize wetting properties, various co-solvents were added to ink formulation. The most promising results were obtained using DPMA (35%) and TEGO WET KL 245 as wetting agents (0.5%). To obtain conductive metallic structures, we used thermal sintering by heating the metallic patterns deposited on a glass. After sintering at 250 °C for 15 min. the resistivity value was found to be 6.8·10¬-4 Ω∙cm.

 

[400] USING VERTICALLY ALIGNED ZINC OXIDE NANOWIRE ARRAYS AS A TEMPLATE FOR METAL SULFIDE NANOTUBE ARRAYS

 

Michael Volokh1

1 Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology

USING VERTICALLY ALIGNED ZINC OXIDE NANOWIRE ARRAYS AS A TEMPLATE FOR METAL SULFIDE NANOTUBE ARRAYS
Michael Volokh, Mahmud Diab, Kobi Flomin, Pazit Rukenstein, and Taleb Mokari*
Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.

High surface area semiconductor nanostructures are important constituents in energy-related applications such as photovoltaics, water splitting, catalysis, and batteries. We use a simple atmospheric-pressure chemical vapor deposition (CVD) system to control the filling and coating of ZnO nanowire (NW) array templates with metal-sulfide shells to create hybrid nanostructures.1 The reactants of the CVD are single-source precursors (SSP). Using different SSPs allowed us to synthesize multi-component structures such as NWs coated with alloy-shell
or multi-shell structures.
Since the zinc oxide is an amphoteric material, applying a basic or acidic environment, allows the dissolution of the ZnO NW template. We used this phenomenon to create different vertically aligned nanotube (NT) arrays such as CdS, ZnS, and CdS-ZnS. The resulting NTs are high-quality polycrystalline nanostructures.
Herein, we present the synthesis and
structural characterization of the different structures. Furthermore, an electrochemical characterization proves the increased surface area of the discussed NTs.

1. Volokh, M.; Diab, M.; Magen, O.; Jen-La Plante, I.; Flomin, K.; Rukenstein, P.; Tessler, N.; Mokari, T. Coating and Enhanced Photocurrent of Vertically Aligned Zinc Oxide Nanowire Arrays with Metal Sulfide Materials. ACS Appl. Mater. Interfaces 2014, 6, 13594–13599.

 

[404] NANODIAMOND-BASED DIAGNOSTIC SYSTEM FOR ULTRASONIC MONITORING OF WATER QUALITY

 

Abba Priev1, Yechezkel (Chezy) Barenholz2

1 Laboratory of Liposomal and Membrane Research; Hebrew University – Hadassah Medical School
2 Institute of Medical Research Israel-Canada (Imric), ; The Hebrew University of Jerusalem

Nanodiamond-based Diagnostic System for Ultrasonic Monitoring of Water Quality

Abba Priev and Yechezkel Barenholz
Laboratory of Liposomal and Membrane Research, IMRIC, Hebrew University – Hadassah Medical School, Jerusalem, Israel

A nanoparticle-based diagnostic kit for real-time ultrasonic monitoring of pathogens and toxins in water has been developed. The device employs a dual mode of operation of high-intensity acoustic waves for concentration of the pathogens in a central node, and low-intensity acoustic waves for precise compositional analysis of nanoparticles (NPs) after their binding to pathogens or toxins. Acoustic acceleration of the immunoassay brings about separation between free and bound antigen in less than one minute when high-density NPs such as nanodiamonds are used. At present, it takes at least 24 hours to detect the presence of pathogens (e.g. coliforms in water reservoirs) by microbiological assays.
We are exploring NP-based diagnostic kits for ultrasonic continuous monitoring of antigens and other biological agents. We have improved sensitivity and reduced the time required for the biological agents’ detection by monitoring biological agents in the sample by capturing and further acoustic analysis of the NP immune complexes. Acoustic pressure is used for capturing and separating the biological agent-NP complexes from the free NPs, and the measurements of acoustic properties are used for precise analysis. The developed NP-based systems for acoustic identification of bacteria or toxins uses Abs immobilized on the NP which interact with the pathogen in the online flow system. High accuracy for sound velocity measurements (up to 0.0002%) and sound attenuation (of about 0.2%) have been used for testing of different toxins and bacteria. Comparative analyses of the ultrasonic method with standard immunoassay techniques have produced linear calibration curves for major components, with correlation coefficients higher than 0.98. It is thus possible to monitor the toxins, viruses and bacteria in water and also to measure physical properties such as conductivity, viscosity, compressibility and density.

 

[414] GRAPHENE QUANTUM DOTS PRODUCED BY MICROFLUIDIZATION

 

Matat Buzaglo1, Michael Shtein2, Oren Regev3

1 Department of Chemical Engineering, Ben Gurion University; Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University
2 Ben-Gurion University of the Negev; Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University
3 Department of Chemical Engineering, Ben-Gurion University of the Negev; Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University

Graphene Quantum Dots Produced by Microfluidization
Matat Buzaglo,1, Michael Shtein, 2 and Oren Regev 1, 2*
1Department of Chemical Engineering and 2Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, Israel
The unique physical properties of graphene quantum dots, including their controllable photoluminescence, flexible structure, biocompatibility and photostability, make them highly desirable for novel applications, such as flexible photovoltaics and bioimaging.
However, the commercialization of these next–generation quantum dots is limited because their production is highly complex and costly. Here, we present for a first time, a purely mechanical method for top-down fabrication of graphene quantum dots.
During a microfluidizer-based “top-down” fabrication, millimeter-sized graphite flakes are fragmented into zero-dimensional nano-sized dots due to high shear rates (>107 sec-1) generated by pressurizing the graphite-aqueous suspension through micro-sized channels. The as-prepared graphene quantum dots are non-functionalized and exhibit excitation-independent photoluminescence.
This facile, environmentally friendly, and scalable method provides an ideal framework for substantial progress toward large-scale production and commercialization of graphene quantum dots-based applications.

 

[415] THE CRITICAL ROLE OF NANOTUBE SHAPE IN CEMENT COMPOSITES

 

Roey Nadiv1, Michael Shtein2, Maor Refaeli3, Alva Peled3, Oren Regev4

1 Ben-Gurion University of the Negev; ilse Katz Institute for Nanoscale Science & Technology

2 Ben-Gurion University of the Negev; Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University
3 Ben-Gurion University of the Negev; Ben-Gurion University of the Negev
4 Department of Chemical Engineering, Ben-Gurion University of the Negev; Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University

The Critical Role of Nanotube Shape in Cement Composites
Roey Nadiva*, Michael Shteina,b, Maor Refaelic, Alva Peledc and Oren Regeva,b
aDepartment of Chemical Engineering, bIlse Katz Institute for Nanoscale Science and Technology, cDepartment of Structural Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
* E-mail address: [email protected] (Roey Nadiv).
Abstract
The growing availability of nanotubes and the increased knowledge about their loading in polymers have prompted the incorporation of nanotubes in cementitious matrices. We explored the effects of loading straight tungsten di-sulfide nanotubes (WS¬2¬NT) or waved carbon nanotubes (CNT) in cementitious matrices and found that their inclusion in these composites at exceptionally low concentrations (0.063 vol% and 0.15 vol% for WS2NT and CNT, respectively) enhanced the composite’s mechanical properties, including compressive and flexural strengths (25-38%) and toughness (67-90%). Thermal analysis and electron microscopy indicated that nanotube incorporation in cementitious matrices also accelerated hydration reaction kinetics. We showed that the straight WS2NTs bridged pores and cracks more effectively than the waved CNTs, which resist crack propagation via an anchoring mechanism. A comparison to representative cement nanocomposite systems shows that nanotubes, offer better reinforcement efficiencies than particulate nanomaterials, yielding high mechanical properties enhancement at low concentration.

 

[421] GRAPHENE RIBBONS FROM GRAPHITE: THE EFFECT OF DISPERSANT STRUCTURE

 

Maxim Varenik1, Micah Green2, Oren Regev1

1 Department of Chemical Engineering, Ben-Gurion University of the Negev; Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University
2 Artie Mcferrin Department of Chemical Engineering; _

Graphene ribbons from graphite: the effect of dispersant structure
Maxim Varenika, Micah J. Greenc* and Oren Regeva,b*
aDepartment of Chemical Engineering, bIlse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
cArtie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122, USA

Dispersants in sonication-assisted exfoliation of graphite into graphene not only stabilize graphene sheets in aqueous solutions, but can also direct fragmentation and template graphene structure. Graphite was exfoliated in the presence of different pyrene derivatives. Dispersions were analyzed using various electron microscopy techniques (cryogenic and room temperature transmission electron microscopy, scanning electron microscopy), Raman, and zeta potential measurements. Stable dispersions prepared using 1-pyrenebutyric acid (PBA) contain graphene ribbons (GR), consisting of individual GR ~0.5 µm in width and several microns in length, while other pyrene derivatives produced graphene flakes. A possible formation mechanism relates to dispersant’s ordered assembly on top of the graphite induced by its two-segment structure, leading to cracking only along certain vectors; these cracks propagate and eventually template the graphene down to GRs and other anisotropic graphene flakes. Additionally, the carboxylic moiety in PBA makes it possible to tune the GR’s zeta potential by changing the pH. Lowering the pH below a critical value causes aggregation, which can be reversed by restoring the original pH value. These ribbons could be applied as fillers in composite materials, foams, and films.

KEYWORDS: Graphene; Pyrene; Dispersant; cryo-TEM; Graphene Ribbon; Graphene Production

 

[425] SELF-ASSEMBLY OF BOTTLEBRUSH BLOCK COPOLYMERS AND GOLD NANOPARTICLES IN THIN FILMS

 

Yaron Aviv1, Roy Shenhar1

1 The Hebrew University of Jerusalem; Givat Ram

Self-assembly of Bottlebrush Block Copolymers and Gold Nanoparticles in Thin Films
Yaron Aviv and Roy Shenhar*
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel

The research on block copolymer-nanoparticle composites has attracted considerable interest in the last two decades. Block copolymers consisting of two chemically distinct polymers joined together by a covalent bond self-assemble upon annealing into various ordered microstructures (lamellae, cylinders or spheres), with periodicities on the scale of 2-200 nm that are dictated by the volume fractions of each blocks. The periodic nanostructures formed by the self-assembly of BCPs can be used to organize nanoparticles (NPs). The nanoparticle surface can be modified to interact selectively with one block of the copolymer, enabling the creation of periodic NP arrays, where the NPs are segregated in the domains formed by this block.
Bottlebrush block copolymers (BB BCPs) represent a new class of polymers with a unique, three-dimensional and highly tunable molecular architectures, which upon self-assembly form well segregated periodic nanostructures. The aim of this research is to push the limits of BCP/NP assembly by employing BB BCPs in order to achieve nanoparticle arrays with greater order (Figure 1). In this poster, initial results on the assembly of polystyrene-block-polylactide BB BCP with gold NPs will be discussed and compared to the assembly with the corresponding linear block copolymer.

Figure 1. Co-assembly of Au nanoparticles with bottlebrush block copolymers.

 

[426] DETECTING MOLECULES OF BIOLOGICAL INTEREST VIA SOLID-STATE NANOPORES

 

Abeer Karmi1

1 Hebrew University ; Institute of Chemistry, and the Centre for Nano Science and Nanotechnology

Detecting Molecules of Biological Interest via Solid-State Nanopores
Abeer Karmi1, Dvir Rotem1, Liron Nuttman2, Noam Attias2, Oded Shoseyov2 and Danny Porath1*
1. Institute of Chemistry and Center for Nanoscience and Nanotechnology, the Hebrew University of Jerusalem, Israel.
2. Institute of Plant Science and Genetics in Agriculture, Food and Environmental Science, the Hebrew University of Jerusalem, Rehovot, Israel.

In the last twenty years, nanopores have become known for their sensing abilities. They offer sensitivity, selectivity and rapid detection of analytes. Nanopore-based sensors have plenty of uses in medical diagnosis and personalized medicine. Nanopores have proven to be useful in improving and developing the field of DNA sequencing. Low cost and high speed sequencing impacts biomedical research that can aid the development of several new genomic and technological studies.
Solid state nanopores are fabricated by drilling through a thin insulating membrane composed of Si3N4 using HR-TEM. The membrane is then placed between two chambers filled with electrolyte solution. The desired analyte can be driven through the pore by voltage application, and ionic current flowing through the pore is monitored. When an analyte is translocated through the pore, a blockage in the ionic current, which is typical to the analyte, is observed. We modify these nanopores to adjust them for various applications. For instance, we exploring a hybrid pore with an extremely stable ring-shaped protein, SP1 (stable protein 1), which is positioned on top of the pore. We concentrate on slowing down DNA translocation through this hybrid pore in order to sequence DNA

 

[427] SOLAR SYNTHESIS OF PBS-SNS2 SUPERSTRUCTURE NANOPARTICLES

 

Olga Brontvein1

1 Weizmann Institute of Science; Materials and Interfaces

SOLAR SYNTHESIS OF PbS-SnS2 SUPERSTRUCTURE NANOPARTICLES
Olga Brontvein1, Ronit Popovitz-Biro2, Daniel Feuerman3, Reshef Tenne1 and Jeffrey M. Gordon3,4,*
1. Department of Materials and Interfaces, Weizmann Institute of Science, P.O. Box 26, Rehovot, Israel.
2. Electron Microscopy Unit, Weizmann Institute of Science, P.O. Box 26, Rehovot, Israel.
3. Department of Solar Energy and Environmental Physics, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Israel.
4. The Pearlstone Center for Aeronautical Engineering Studies, Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beersheva, Israel.
5.
Inorganic fullerene-like structures and inorganic nanotubes became a world popular research subject in recent years. So far a number of synthetic routes have been developed for production of inorganic nanotubes made of misfit layered compounds.
A new procedure for the synthesis of PbS-SnS2 misfit fullerene-like nanoparticles is represented here1. This is a fundamentally distinct type of misfit nanostructure, closed-caged nanoparticles from PbS-SnS2, which, had neither been proposed nor synthesized previously. The unique reactor conditions created in the solar furnace are found to be particularly conducive to the formation of these nanomaterials. Detailed structural and chemical characterization revealed a spontaneous inside-out formation mechanism, with a broad range of nonhollow fullerene-like structures starting at a diameter of ∼20 nm and a wall thickness of ∼5 layers.

Figure 1: High-resolution STEM HAADF image of a single PbS-SnS2 superstructure.
1. O. Brontvein, A. Albu-Yaron, M. Levy, D. Feuerman, R. Popovitz-Biro, R. Tenne, A. Enyashin and J. M. Gordon, ACS Nano, 2015, 9, 7831-7839.

 

[428] POLYMER NANOCOMPOSITE :IMPROVING GAS BARRIER AND MECHANICAL PROPERTIES

 

Sivan Peretz Damari1, Oren Regev2

1 Chemical Eng.; Ben Gurion University
2 Department of Chemical Engineering, Ben-Gurion University of the Negev; Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University

Polymer nanocomposite :Improving Gas barrier and mechanical properties
Sivan Peretz Damari1 and Oren Regev 1, 2
1Department of Chemical Engineering and 2Ilse Katz Institute for Meso and Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, Israel

Abstract
Polymer based nanocomposites (PNC) have become a prominent area of current research and development. This material exhibits substantial property enhancement at much lower loading than polymer composite with conventional micro scale fillers (such as glass or carbon fiber). Reduction in polymer permeability is both fundamentally important and a practical necessity in the polymer industry. The barrier properties of polymers can be significantly altered by inclusion of impermeable lamellar fillers with sufficient aspect ratio to alter the diffusion path of gas-penetrant molecules. One of the most common barrier materials is clay (such as montmorilonite) , however, it is less effective as water vapor barrier since it absorb water and swells. Therefore, we suggest using graphene nanoplatelets as barrier fillers. The tremendous interest in graphene lies in its one-atom-thick nature, with a densely packed conjugated structure that is capable of exhibiting unprecedented electrical, thermal, and mechanical properties. In addition high aspect ratio (l/d > 1000) graphene are known to be impermeable to most gases and liquids, much like clay, making them of great interest for the preparation of barrier nanocomposites.
In this study we investigate the effect of graphene sheets with various aspect ratio on the barrier and mechanical property of polyurethane. We have demonstrated ~40% reduction for water vapor permeability and also achieved ~70% fracture toughness enhancement.

 

[434] IN SITU HIGH PRESSURE RAMAN AND FLUORESCENCE INVESTIGATION ON MONOLAYER WS2

 

Qiang Zhou1

1 College of Physics; State Key Lab of Superhard Materials

In situ high pressure Raman and fluorescence investigation on monolayer WS2
Bo Han, Fangfei Li, Yuanbo Gong, Xiaoli Huang, Hanxue Gao, Qiang Zhou*
College of Physics, State Key laboratory of Superhard Materials, Jilin University P.R. China.

It is beyond the question that transition metal dichalcogenides (TMD) such as tungsten disulfide are in possession of several qualities in photonic, mechanical and particularly electronic fields. Differentiating from its bulk counterparts that are in-direct semiconductor, the monolayer of WS2 has a direct band gap around 1.94eV and thus a prominent photoluminescence. The mechanism of these qualities due to structural changes is crucial for future application.
In this study, WS2 monolayers are well synthesized by a traditional CVD methodology. We exert quasi-hydrostatic pressure on WS2 monolayer ticking up to 20GPa by a diamond anvil cell(DAC). Lattice dynamic properties are examined by Raman Scattering which shows significant blue-shift in proceeding and a premier in-plane E2g mode splitting at 2.18GPa, indicating a structural deformation of the lattice. Further implied from the PL spectrum, the rich band structure undergoes an apparent blue-shift from 640nm to 620nm, suggesting an enlargement of the band gap. Our study allows for investigation of few layered WS2, other 2dimension TMD and further device application of this kind of materials.

Acknowledgment
The authors graciously acknowledge the National Natural Science Foundation of China for funding (grant nos. 11274137, 51032001, 11074090, 51025206, 11204100 and 11474127), National Basic Research Program of China (no. 2011CB808200), Program for Changjiang Scholars and Innovative Research Team in University (no. IRT1132), and National Fund for Fostering Talents of Basic Science (no.J1103202).

Corresponding author Email: [email protected]

 

 

 

 

[437] MAGIC SIZE III-V SEMICONDUCTOR CLUSTERS: SYNTHESIS AND PROPERTIES

 

Jiajia Niing1, Uri Banin2

1 The Hebrew University of Jerusalem; Institute of Chemistry
2 Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem ; The Hebrew University of Jerusalem

Magic Size III-V Semiconductor Clusters: Synthesis and Properties
Jiajia Ning, Uri Banin
Institute of Chemistry and the Center for Nanoscience and Nanotechnology,
The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Magic size semiconductor clusters represent a molecular limit for semiconductor nanocrystals. Such clusters, previously mostly studied for II-VI and IV-VI semiconductors, are characterized by well defined size with particular stability often assigned to their closed-shell architecture. is formed only by clusters containing a well-defined number of atoms. Here we synthesized magic size nanoclusters of III-V semiconductors which have been rarely studied, including both magic sized InP nanocrystals (MInP NCs), and InAs clusters. The systems were characterized by absorption, Xray diffraction, and their thermal stability in the synthesis.
Furthermore due to large surface to volume ratio inherent to the clusters, the emission of MInP NCs is very weak. To address this, we also developed and studied the growth of protective high band gap ZnS shell onto the MInP NCs via layer-by-layer method. The properties of such coated MInP NCs were characterized. Transition between different emission properties was observed using both spectral measurements and fluorescence lifetimes. Several mechanisms for the observed emission behavior and the transition will be discussed.

Keywords: magic size nanoclusters, emission, InP nanocrystals, core/shell, dopant

 

[439] COPPER SULFIDE NANOCRYSTALS LEVEL STRUCTURE AND ELECTROCHEMICAL FUNCTIONALITY TOWARDS SENSING APPLICATIONS

 

Kathy Vinokurov 1

1 The Hebrew University of Jerusalem; The Hebrew University of Jerusalem

Copper sulfide nanocrystals level structure and electrochemical functionality towards sensing applications

Kathy Vinokurov,1 Orian Elimelech,1 Oded Millo2 and Uri Banin1

1Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
2Racah Institute of Physics and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

The level structure of 7 and 14 nm in diameter copper sulfide nanocrystals were investigated by correlating scanning tunneling spectroscopy and cyclic voltammetry data in relation to sensing applications. Upon oxidation of Cu2S nanocrystals in the low-chalcocite phase, correlated changes are detected by both methods. The cyclic voltammetry oxidation peak of Cu(1+) down shifts, while in-gap states, adjacent to the valence-band edge, appeared in the tunneling spectra. These changes are attributed to Cu vacancy formation leading to a Cu depleted phase of the nanocrystals.
The relevance of the oxidation to the use of copper sulfide nanocrystals in hydrogen peroxide electrochemical sensors was also studied. A significant decrease in the electrochemical sensitivity for the oxidized copper-deficient Cu2-xS phase was observed. This effect should be taken into consideration when considering use of copper sulfide nanocrystals towards bio-compatible electro-sensing systems.

 

[440] ELECTRONIC PROPERTIES OF NANOCRYSTALLINE Π-SNS AND Π-SNSE – A NEW CUBIC PHASE OF TIN SULFIDE AND TIN SELENIDE

 

Elad Segev1

1 Ben-Gurion University of the Negev; Ilse Katz Institute for Nanoscale Science and Technology

Electronic Properties of Nanocrystalline π-SnS and π-SnSe – a new cubic phase of Tin Sulfide and Tin Selenide

Elad Segev‡, Ran E. Abutbul†‡, Yuval Golan†‡ and Guy Makov†‡
†Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
‡Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
We report on structural, energetic and electronic properties of a new phase in the binary SnX (X=S,Se) systems. The structure and atomic positions of the -SnS,Se phase consisting of 64 atoms per unit cell were relaxed using DFT-PBE calculations and showed a stable structure which is analogous to the recently reported cubic phase of SnS (a0 = 11.595Å, No. 198) and may be considered as a distorted rocksalt phase. The thermodynamic stability was considered in comparison with the bulk stable orthorhombic phase (also considered a distorted rocksalt phase) with 8 atoms per unit cell and the ideal rock salt phase. Band structure calculations indicate that the new phases have larger bandgaps than the ideal rocksalt phase indicating a possible stabilisation mechanism. The value obtained for the bandgaps are in good agreement, possibly fortuitous, with the measured bandgaps.

 

[445] ZINC CHALCOGENIDE SEMICONDUCTOR NANOCRYSTALS

 

Alisa Hagen1

1 Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

Alisa Hagen1,2, Guohua Jia1,2, Inna Popov2 and Uri Banin1,2
1Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
2Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
The bottom-up approach for the synthesis of semiconductor nanocrystals provides size and shape controlled particles with tunable properties for numerous applications. While the syntheses of cadmium chalcogenide nanocrystals are well developed in the literature, there is still a lack of reports involving zinc chalcogenide systems of different morphologies and structures.
The development of nanocrystals containing zinc is highly important for a variety of applications in which cadmium free structures are advantageous; for instance, zinc chalcogenide nanocrystals could be used as sensors in biological imaging. Here, we report a general strategy for synthesizing quasi one-dimensional (1D) nanorods and unique structure of nanorod couples of ZnSe via a colloidal chemical synthetic approach. Wurtzite ZnSe nanorod couples connected by twinning structures are synthesized by means of a self-limited assembly process, whereas 1D nanorods are synthesized by a ripening process starting from ultrathin nanowires through thermodynamically driven material diffusion. The effects of different synthesis parameters will be presented and will be supported by different characterization methods, such as transmission electron microscopy, spectroscopic measurements, XRD, etc.
We are now working on synthesizing more particular rod and rod couple structures such as semiconductor-metal hybrid nanorod systems in order to enable the design of high quality nanocrystals which in the future could be used for photocatalysis and in optoelectronic applications.

References:
G. Jia, A. Sitt, G.B. Hitin, I. Hadar, Y. Bekenstein, Y. Amit, I. Popov and U. Banin “Couples of colloidal semiconductor nanorods formed by self-limited assembly“, Nature Materials 13, 301–307 (2014)
G. Jia, U. Banin “A General Strategy for Synthesizing Colloidal Semiconductor Zinc Chalcogenide Quantum Rods“, J. Am. Chem. Soc., 2014, 136 (31), pp 11121–11127

 

[446] HEAVILY DOPED SEMICONDUCTOR COLLOIDAL NANOCRYSTALS – IMPURITY DOPING AND ITS IMPLICATIONS ON THE RESULTING STRUCTURE

 

Yorai Amit1

1 Institute of Chemistry, Hebrew University, Jerusalem 91904,Israel. ; Huji

Heavily Doped Semiconductor Colloidal Nanocrystals – impurity doping and its implications on the resulting structure
Yorai Amit1,2, Yuanyuan Li2, Anatoly I. Frenkel*,2, and Uri Banin*,1

1 The Institute of Chemistry and The Center for Nanoscience and Nanotechnology, Hebrew University, Jerusalem 91904, Israel.
2 The Department of Physics, Yeshiva University, New York, New York 10016, United States
Tuning of the electronic properties of pre-synthesized colloidal semiconductor nanocrystals (NCs) by doping plays a key role in the prospect of implementing them in advanced transistors, photodiodes and photodetectors. While routes for impurity doping of semiconductor NCs have already been introduced, the understanding of the doping process, the nature of interaction between the impurity and host atoms, and the conditions affecting the solubility limit of impurities are still unclear. Here, we used a post-synthesis diffusion-based doping reaction to introduce different impurity atoms, at various concentrations, into InAs NCs. X-ray absorption fine-structure (XAFS) spectroscopy was employed to determine the location of the impurity, enabling a systematic study of the impurity concentration dependence as a function of the size of the host NC on the identified impurity site to derive a self-consistent picture of the resulting structure While Cu doping previously revealed purely interstitial doping for a very wide range of impurity/NC ratios, doping with Ag impurities was found to be a heterogeneous system where the impurities initially dope the NC, through a substitutional mechanism, until the “solubility limit” is reached after which the rapid growth and formation of metallic structures is identified. These findings establish the reproducibility as well as the subtlety of the diffusion-based doping strategy. The understanding of the doping mechanism and insights on the impurity solubility limit are of grave importance when attempting to implement such heavily doped semiconductor NCs in various optoeldctronic devices.

 

[477]   PbSe/PbS alloyed quantum dots

 

Arthur Shapiro and Efrat Lifshitz^*

Schulich Faculty of Chemistry, Russell Berrie Nanotechnology Institute, Solid State Institute, Technion-Israel Institute of Technology, Haifa 3200013, Israel (*[email protected])

 

Lead chalcogenide (group IV-VI semiconductors) colloidal quantum dots (CQDs) have raised scientific and technological interest due to their optical tunability in the infrared (IR) spectral regime (0.7-3.5µm).This wide tunability range is a result of a narrow band gap and a large exciton Bohr radius (e.g. a_b(PbS)= 18 nm, and a_b(PbSe)= 46 nm). Moreover, they have relatively small effective masses of both the hole and electron. Therefore, they provide a unique opportunity for fundamental studies of strongly confined quantum systems.

However, the different lattice constants of both materials, PbSe and PbS causes to a big strain in the interface, leading to a low values of quantum yield, etc.

In this work we show how to achieve high quality PbSe/PbS CQDs, with sharp size distribution and characterize them by using spectroscopical, structural and compositional characterization methods. Moreover, an evidence for the alloy is given  by different means.

 

[453] FACETING IN MULTI-WALLED NANOTUBES

 

itai leven1

1 Tel Aviv University; Tel Aviv University

Faceting in layered nanotubes
I. Leven1,2*, R. Guerra3,*, A. Vanossi3, E.Tosatti3, Oded Hod1,2
1 Department of Physical Chemistry, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
2 The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, IL 6997801
3 International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy;

Abstract:
Nanotubes hold great promise for the miniaturization of advanced technologies. Their exceptional physical properties are intimately related to their detailed morphological and crystal structure. Importantly, circumferential faceting of multi-walled nanotubes serves to reinforce their mechanical strength and alter their tribological and electronic properties. Here, nanotube faceting is fully rationalized in terms of interlayer registry patterns. We find that, regardless of the nanotube identity, faceting requires chiral angle matching between adjacent layers. Above a critical diameter that corresponds well with experimental findings, achiral multi-walled nanotubes display evenly spaced extended axial facets, the number of which is determined by the interlayer difference in circumferential unit cells. Elongated helical facets, most commonly observed in experiment, appear in nanotubes exhibiting a small interlayer chiral angle mismatch. In the case of uncorrelated wall chiralities faceting is suppressed and surface corrugation induced by the Moiré superlattice is obtained in excellent agreement with experiment. It is therefore evident that gaining control over their interlayer registry matching provides a route for the mechanical enforcement as well as tribological and electronic properties tuning of MWNTs.

 

[454] SCALABLE NONMANUFACTURING OF MONODISPERSE QUANTUM DOTS

 

richard robinson1

1 Materials Science Department.; 214 Bard Hall

Richard Robinson
Associate Professor
Cornell University
Ithaca, NY USA
http://robinson.mse.cornell.edu/

Over the last two decades, nanoparticle synthesis has progressed significantly, to the point of creating a multitude of new shapes and compositions, with tight size controls. The emergence of NP-enabled technologies has created a growing demand for scalable NP synthesis methods. Unfortunately, the conventional synthesis procedure (“hot-injection”) is optimized for laboratory scale studies and does not easily scale, limiting the incorporation of nanoparticles into technology. Scaling up the hot-injection presents important, and yet unresolved, challenges. Specifically, the stringent demand for rapid precursor mixing (due to fast reaction kinetics) pose a critical barrier to production as larger reactor volumes, hindering reproducibility and control. We embraced these challenges as an opportunity to investigate new synthesis methods that upend the conventional hot-injection technique.

In this talk I’ll discuss our work on new methods for nanoparticle scale-up synthesis reactions, with the goal of producing nanoparticles for LED lighting. Our group has developed a rational method for the synthesis of monodisperse metal sulfide nanocrystals in organic solutions by using (NH4)2S as a sulfide precursor. The method enables low temperature (< 100 oC) syntheses, open-air reactions, high conversion yields (>90%), and large-scale production of monodisperse nanocrystals can be synthesized in a single reaction (more than 100x that of the conventional “hot-injection” method).
I will also discuss our scalable results using high viscosity in a “heat-up” synthesis. These new highly-viscous regimes alter the kinetics of the reaction and diverge from the classical Le Mer model on solution-phase synthesis. Specifically, we synthesize high-quality metal sulfide NPs (< 7% relative standard deviation for Cu2-xS, CdS, and PbS), and demonstrate up to a 1000 fold increase in Cu2-xS NP production (>200 g) relative to the current field of large-scale (0.1-5 g yields) and lab-scale (<0.1 g) efforts. We provide an explanation of our results by probing the interplay between chemical, thermal, and rheological properties on NP growth and dissolution.

 

[457] POLVINYL ALCOHOL HYDROGELS REINFORCED WITH RESILIN-CELLULOSE BINDING DOMAIN-CELLULOSE NANOCRYSTALS

 

Tiffany Abitbol1, Amit Rivkin2, Tal Ben-Shalom1, Oded Shoseyov1

1 The Hebrew University of Jerusalem; Robert H. Smith Faculty of Agriculture, Food and the Environment
2 The Hebrew University of Jerusalem ; Robert H. Smith Faculty of Agriculture, Food and the Environment

Cellulose nanocrystals (CNCs) and resilin possess distinct yet complimentary properties that

can be harnessed to prepare new, functional materials. CNCs are rod-shaped, highly

crystalline nanoparticles that represent the main structural, load-bearing component in

trees, whereas resilin is a rubbery material found in the organs of anthropods,

whose function require both elasticity and resilience, for example in the femur of fleas.

Recombinant resilin (res) from Drosophila Melanogaster has been genetically engineered to include a

cellulose binding domain (CBD), which provides a conduit to link resilin to CNCs, with binding

efficiencies of up to 20% of the total CNC mass. Here, we present results of hydrogels

prepared from res-CBD-CNCs and polyvinyl alcohol by freeze-thaw cycling, specifically swelling behavior,

crystallinity, mechanical properties, and morphology, with the end goal of the work to produce novel

materials for biomedical applications.

 

[462] UNWRAPPING CORE–SHELL NANOWIRES INTO NANORIBBON-BASED SUPERSTRUCTURES

 

Guy Davidi1

1 Tel Aviv University; Tel Aviv University

Over the last decade one-dimensional nanostructures have attracted considerable attention as promising building blocks for nanoscale devices, owing to their novel physical and chemical properties. In particular, nanoribbons (NRs) are of major interest due to their shape, comprised of a rectangular cross-section on a nanometer scale that can provide unique properties for optical, mechanical and electrical devices. Several experiments on III-V and oxide semiconductor nanoribbons have already shown promising properties, such as the wave-guiding of photons, lasing action, nonlinear polarization and high mechanical flexibility. Although these approaches have been proven to be effective, the controlled synthesis of semiconductor nanoribbons still remains a challenge.
Herein, we demonstrate a simple, and yet robust, method for the fabrication of high quality single-crystal silicon nanoribbons by the unwrapping of core/shell nanostructures. The method is based on the controlled unfurling of germanium core/silicon shell nanowires by an anisotropic plasma step, followed by etching of the sacrificial germanium core, under wet or dry conditions. Our method allows tight control over the physical and chemical properties of the fabricated nanoribbons, such as lateral and horizontal dimensions, dopant concentration control along all directions, formation of multi-layered ribbons, orthogonal chemical modification of ribbon faces etc. Lastly, the method is not only limited to the fabrication of silicon nanoribbons, but can also be easily applied to a wide range of semiconductor and dielectric materials.

 

[466] RAMAN SCATTERING FROM SINGLE WS2 NANOTUBES EMBEDDED WITHIN STRETCHED PVDF SUBMICRON FIBERS

 

Olga Grinberg1, Alla Zak1

1 Holon Institute of Science; Holon Institute of Science

Raman scattering from single WS2 nanotubes embedded within stretched PVDF submicron fibers

Olga Grinberg1, Ron Avrahami2, Eyal Zussman2, Tsachi Livneh3, Alla Zak1
1Holon Institute of Technology, 52 Golomb St., P.O.Box 305, Holon, Israel
2Department of Mechanical Engineering, Technion – Israel Institute of Technology, Technion City – Haifa 32000, Israel
3Department of Physics, Nuclear Research Center, Negev, P.O. Box 9001, Beer-Sheva, 84190, Israel

Multiwall inorganic WS2 nanotubes (INT-WS2) possess high mechanical strength, high flexibility, and interesting surface chemistry. Significant improvement of crystallization, mechanical and tribological behavior of various polymers can be achieved by the formation of nanocomposites upon the embedment of INT within their structures. The long PVDF (polyvinylidene difluoride) – WS2 composite fibers used in this study, were obtained by electrospinning, and featured the diameter in the range of 0.5–1.5 µm. The majority of the embedded WS2 INTs have the length of 5 – 10 µm and diameter of 50 – 120 nm.
The objective of this work is to investigate what can be learned on the nature of INT-polymer interactions, by exploring the effect of fibers’ stretching on the Raman scattering of single nanotube, embedded within a single PVDF fiber. A computer controlled load-cell set-up, which was build for this study, enables the submicron to mm range stretching of composite fibers with simultaneous measuring of its Raman scattering response under a microscope. For this study a well-equipped Horiba LabRam HR Evolution Raman scattering spectrometer with multiple (785, 633, 532, 325 nm) excitation energy sources was used. We present here the results measured on the five different single fibers, where we detected from 3 cm-1 to 5 cm-1 red shift in the frequencies of two main bands of WS2, one – comprises of the 2LA(M) and E2g vibration modes and second – vibration mode of the A1g symmetry. The shift occurs between the fibers’ “relaxed” and “almost torn” states. The nature of this response is currently under study.

 

[467] SILICON NANOWIRES GROWTH BY CONFINEMENT-GUIDED METHOD

 

Roi Vizel1, Alon Kosloff2, Fernando Patolsky3

1 The Department of Materials Science and Engineering; Center for Nanoscience and Nanotechnology
2 Tel Aviv University; School of Chemistry
3 School of Chemistry; School of Chemistry

Silicon Nanowires Growth by Confinement-Guided Method

In the recent years, semiconducting nanowires have attracted much interest, and were widely explored for developing electronic, optoelectronic, and biosensing devices, due to their unique properties due to the sub-micron dimensions. Great efforts have been taken for developing a simple, effective, manufacturable large-scale assembly method of nanowires growth with controlled and uniform orientation and dimensions, at spatially well-defined locations, while achieving high quality electrical properties. Even though a major progress has been achieved in this field of research, it still remains the bottleneck challenge for integrating these structures into commercial devices.
Here, we present a simple and robust grow-in-place approach, allowing the positioning and orientation of synthesized nanowires to be precisely controlled by a confinement-guided method. This approach enables the bottom-up synthesis of nanowires through the vapor-liquid-solid (VLS) mechanism, without the need of harvesting or assembling steps. Our method also prevents nanowires contamination through growth in the confinement tunnels, resulting in fine and suitable electrical properties for the intended devices. This method advances the ability of integrating nanowires as building blocks for a broad variety applications, and to exploit their full potential.

 

 

 

 

[471] FUNCTIONAL PEPTIDE ASSEMBLIES ON SURFACES: TOWARDS ENVIRONMENTALLY FRIENDLY ANTIFOULING MATERIALS

 

sivan nir1, Tal Zada2, Meital Reches3

1 Institute of Chemistry, the Hebrew University of Jerusalem; The Harvey M. Krueger Family Center for Nanoscience and Nanotechnology
2 The Hebrew University of Jerusalem; The Hebrew University of Jerusalem
3 The Hebrew University of Jerusalem; The Center for Nanoscience and Nanotechnology

Functional Peptide Assemblies on Surfaces:
Towards Environmentally Friendly Antifouling Materials
Sivan Nir, Tal Zada and Meital Reches*
Institute of Chemistry, The Hebrew University of Jerusalem, Israel
The Harvey M. Krueger Family Center for Nanoscience and Nanotechnology

Biofouling is an undesirable process in which a surface becomes encrusted with organisms and their by-products. This unwanted colonization has a serious impact on marine devices, as it lead to deterioration of the surfaces and can alter fluid flow rates leading to significant increase in cost of marine transportation. In the healthcare system, the attachment of bacteria and biofilm formation on medical devices may lead to a severe infection and consequently death. In the US alone, the American Centre for Disease Control and Prevention (CDC) reported that healthcare-associated infections account for an estimated 1.7 million infections and 100,000 deaths annually.
Many approaches to prevent biofouling have been suggested, however, they suffer from drawbacks such as release of toxic materials to the surroundings, low stability that limits their long-term application or complex and expensive synthesis.

We have recently designed a tripeptide that self-assembles into a nano-metric coating that interfere with the attachment of organisms to the substrate and therefore act as an antifouling agent.
The peptide contains three elements that enable i) its self-assembly into a film, ii) its adsorption onto any substrate and iii) its antifouling activity. The peptide-based coating completely prevented the first stage of biofouling and abolished the adsorption of proteins to a substrate. Moreover, the coating significantly reduced the amount of different bacterial strains adsorbed on the substrate.

 

[478] UNDERSTANDING THE ROLE OF CELLULOSE NANOCRYSTAL SURFACE CHARGE ON RHEOLOGY AND CHIRALITY

 

Doron Kam1, Tiffany Abitbol2, Oded Shoseyov3

1 Robert H. Smith Faculty of Agriculture, Food and Environment ; The Hebrew University of Jerusalem
2 The Hebrew University of Jerusalem; Robert H. Smith Faculty of Agriculture, Food and the Environment
3 The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem; The Hebrew University of Jerusalem

Understanding the role of cellulose nanocrystal surface charge on rheology and chirality
Doron Kam, Tiffany Abitbol and Oded Shoseyov
Robert H. Smith Faculty of Agriculture, Food and Environment
The Hebrew University of Jerusalem, Rehovot

Cellulose nanocrystals (CNCs) are rod-shaped crystals that are extracted by the strong acid hydrolysis of cellulose fibers, which preferentially degrades amorphous regions. The hydrolysis conditions and the cellulose source significantly impact the properties of the resulting particles, including particle size, surface charge and self-assembly.
It was noted that minor differences in CNC production, led to large differences among the final properties of the suspensions. To better understand these effects, we studied the properties of four different CNC suspensions in detail. This study concentrated specifically on the interplay between particle size and surface charge, which give rise to differences in the phase behavior and the rheology of the samples.
During acid hydrolysis with sulfuric acid, acidic sulfate half-ester groups are grafted onto the nanoparticle surface, resulting in a negatively charged particle characterized by an electric double layer. This electrical property plays an important role in the interaction between CNCs and the suspension medium, and between CNCs. The combination of electrostatic repulsion and the attractive effects of van der Waals, hydrogen bonding and cellulose-cellulose interactions are described by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The balance between these interactions determines the dominant force as a function of particle separation.
Considering CNCs, at one extreme, surface charge is zero, attractive forces dominate and aggregation occurs. At the second extreme, electrostatic repulsion dominates leading to a colloidally stable suspension. We propose an intermediate regime, where particles are colloidally stable but attractive interactions exert more pronounced effects. Within this regime, the viscosity and phase behavior of the suspensions is influenced by attractive forces, giving results that are in disaccord with theories describing the electroviscous effect and the phase separation of charged rods.

 

[480] AMORPHOUS PHASE CONTENT IN TITANIA CATALYSTS: QUANTITATIVE MEASUREMENTS AND INFLUENCE ON PHOTOCATALYTIC PROPERTIES

 

Vasily Lebedev1, Daniil Kozlov2, Anton Poluboyarinov1, Irina Kolesnik1, Alexei Garshev3

1 Lomonosov Moscow State University, Department of Materials Science; –
2 Lomonosov Moscow State University; –
3 Lomonosov Moscow State University, Department of Materials Science; Baikov Institute of Metallurgy and Material Science Ras

Amorphous phase content in titania catalysts: quantitative measurements and influence on photocatalytic properties
Lebedev V.A., Kozlov D.A., Poluboyarinov A.S., Kolesnik I.V., Garshev A.V.

Further improvement of the photocatalytic activity (PCA) of titania based catalysts is one of the key research issues in the field of heterogeneous catalysis. Unfortunately, the presence of the “invisible” XRD-amorphous part in the catalysts is often underestimated. This decreases the validity of comparison between different catalysts, because the PCA of the amorphous phase is significantly lower than that of crystalline samples. Therefore, a reliable quantitative method for the amorphous phase analysis is required.
In this study we quantitatively measured the total amorphous phase amount in commercially available P25 Evonik (Degussa) and Hombikat UV100 titania catalysts, as well as in pre-synthesized mesoporous titania by XRD phase analysis of multiple sample/standard mixtures. Furthermore, we could distinguish the water content in the amorphous phase from water adsorbed on the material surface using thermal analysis. Additionally, PCA measurements were performed in liquid in an IceGlass quartz reactor with the use of methyl orange (MO) as a photodegradable agent. A high-pressure Hg bulb (5W) was used for illumination. The pH stabilization was achieved using a phosphate buffer solution (pH 6.7). MO concentration changes were measured every 3-5 sec. in a U-shape flow cell with continuous sampling by a peristaltic pump system. We found the negative correlation between the weight amount of amorphous phase and the PCA of titania catalysts. This result was confirmed by measurements of the annealed samples with the decreased amount of the amorphous phase.
This work was supported by RFBR (grant №15-03-99537 А) and M.V.Lomonosov Moscow State University Program of Development.

 

[490] TEMPERATURE DEPENDENT RAMAN SCATTERING IN CH3NH3PBX3 ΗYBRID PEROVSKITES WITH VARIOUS HALIDE COMBINATIONS

 

Athanassios Kontos1, Ralf Niemann2, Andreas Kaltzoglou1, Petra Cameron2, Polycarpos Falaras1

1 National Center for Scientific Research Demokritos; Institute of Nanoscience and Nanotechnology
2 Department of Chemistry; Department of Chemistry

Temperature dependent Raman scattering in CH3NH3PbX3 Ηybrid Perovskites with various halide combinations
Athanassios G. Kontosa*, Ralf G. Niemanna,b, Andreas Kaltzogloua, Petra J. Cameronb and Polycarpos Falarasa

a Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Athens, Greece
b Department of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
* Corresponding author: [email protected]

This study presents the vibrational properties of single and mixed MAPbX3 (X = Cl, Br, I) perovskites with off-resonance variable temperature Raman measurements. Comparison of results for all perovskite derivatives evidenced emergence of new low frequency vibrational bands indicative of their phase transformation from cubic at 294 K to the orthorhombic phase at 100 K. MAPbBr3, the intermediate species of our halide series, has been further characterized by variable temperature Raman measurements in the entire 100-294 K range (see Figure 1).

Figure 1. micro-Raman spectra of MAPbBr3 for various temperatures (excitation at 785 nm).
Most Raman modes present normal temperature dependence with blue frequency shifts and linewidth narrowing upon reducing the temperature apart from certain methyl ammonium bands: a) the rocking mode (925 cm-1) which presents a steep reduction in the linewidth followed by a plateau for temperatures below the tetragonal I to II phase transition and b) the torsional mode (320 cm-1) which shows abnormal linewidth broadening near the same critical temperature range. The results are analyzed in terms of disorder and different structural orientation of the MA cations, both effects giving implications on the photovoltaic properties of the hybrid perovskites that are considered among the most efficient absorbers in 3rd generation solar cells.

 

[495] ALL-CARBON-NANOTUBE FLEXIBLE NEUROELECTRODES FOR BRAIN STIMULATION AND MONITORING

 

Lilach Bareket1, Moshe David-Pur1, David Rand1, Yael Hanein1

1 Center for Nanoscience and Nanotechnology; Tel Aviv University

All-carbon-nanotube flexible neuroelectrodes for brain stimulation and monitoring

Extensive investigations over the past 50 years revealed the great potential of electrodes for recording and stimulating neuronal signals in the brain. Both implanted and skin biopotential electrodes transduce ionic currents in the tissue to electrons and holes in the electronic device when recording neural activity and vice versa when stimulating the biological tissue. Despite a rapid recent development, contemporary neuronal electrodes are still typified by relatively low signal to noise ratio, low spatial resolution (leading to poor site specificity) and limited biocompatibility. Clearly, further development is needed to make better electrodes suited for seamless integration between electronic devices and neuronal systems.
Here we present a new flexible neuronal electrode device, based entirely on carbon nanotube (CNT) technology, where both the conducting traces and the stimulating electrodes consist of CNT films embedded in a polymeric support. The use of CNTs bestows the electrodes flexibility and excellent electrochemical properties. As opposed to contemporary flexible neuronal electrodes, the technology presented here is robust and the resulting stimulating electrodes are nearly purely capacitive. Recording and stimulation tests with chick retinas as neuronal model validate the advantageous properties of the electrodes and demonstrate their suitability for high-efficacy neuroprosthetics and neural monitoring.

 

[498] EVIDENCE FOR INCREASED FREE ELECTRONS CONCENTRATION IN CU-DOPED INAS NANOCRYSTALS

 

Adam Faust1, Yorai Amit2, Uri Banin3

1 Institute of Chemistry and the Center for Nanoscience and Nanotechnology ; The Hebrew University of Jerusalem
2 Institute of Chemistry, Hebrew University, Jerusalem 91904,Israel. ; Huji
3 Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem ; The Hebrew University of Jerusalem

Following the footsteps of bulk-semiconductor doping and aiming to increase the variety of nanocrystals (NCs) and enhance control over their properties, new synthesis approaches for intentionally introducing impurities to semiconductor NC have been recently developed. Doping NCs differs from bulk semiconductor doping as the dopants are confined to the small dimensions of the NCs and interaction between dopants, seen only in heavily doped bulk semiconductor, can be achieved with only a few dopants in each NC, making it scientifically interesting system to study with possible future applications. The ability to dope InAs quantum dots (QDs) post-synthesis with controlled level of Cu and Ag atoms achieving n- and p-type NCs makes them highly interesting system and suitable for systematic study of the doping effects on optical and electronic properties. Raman scattering is used in the study of bulk-semiconductor doping to locate low concentration doping, doping concentration and free carrier concentration.
We present here Raman scattering study of Cu-doped InAs QDs focused on the doping effect on the modes of the QD. We reveal the Cu doping causes a decrease in scattering intensity of the LO mode, relatively to that of the TO mode, as well as reduction in the LO over-tone. Increased Cu doping level is also accompanied by a shifting of the TO and LO energies suggesting the ionic nature of the In-As bond weakens. Experimental results rule out the Cu local vibrational mode and red shift in phonons energies expected from by DFT calculation. This suggest the effects measured are not due to structural changes in the NC, however, we believe our experimental results are strong evidence for increased concentration of free electrons leading to weakening of the electron-phonon coupling and masking of the ionic bond. Raman scattering measurements on different sizes of InAs QDs imply the doping effect is stronger as the size of the QD decreases.

 

[507] THE INFLUENCE OF CONTACT EFFECTS ON THE SPR PEAK POSITION IN METAL/SEMICONDUCTOR NANOCOMPOSITES

 

Daniil Kozlov1, Vasily Lebedev2, Alexander Polyakov3, Alexei Garshev4

1 Lomonosov Moscow State University; –
2 Lomonosov Moscow State University, Department of Materials Science; –
3 Lomonosov Moscow State University; Faculty of Materials Science
4 Lomonosov Moscow State University, Department of Materials Science; Baikov Institute of Metallurgy and Material Science Ras

The influence of contact effects on the SPR peak position in metal/semiconductor nanocomposites
Kozlov D.A., Lebedev V.A., Polyakov A.Yu., Garshev A.V.
Zinc oxide and titania are important photocatalysts for photodegradation of organic wastes under UV-light illumination. There are different approaches to expand their scope of applicability by photosensibilisation, and one of them is the decoration of common catalysts with noble metal nanoparticles. In our work we used three methods of the decoration of initial matrices by silver and gold nanoparticles: the Turkevich method, the reduction by borohydride and the one-step hydrothermal synthesis. These methods result in different contacts between metallic and semiconducting nanoparticles.
Obtained nanocomposites were studied with UV-vis spectroscopy, XRD, SEM, TEM with local EELS and EDX-analysis. The photocatalytical activity was measured by photodegradation reaction of methyl orange. The EEL spectra were collected using high resolution transmission electron microscope (Zeiss Libra 200FE) with monochromator and omega-filter. High energy resolution allows us to measure SPR peak position in visible range. Moreover, it is possible to collect simultaneously plasmonic peaks and zero-loss peak, which allows one to calculate the relative thickness of the sample. Therefore, it is possible to collect low-energy EEL spectra from individual nanoparticles with respect to their thickness.
The obtained composites demonstrate different photocatalytic activities. It may be caused by the different contacts in the composites. In the case of slow reduction, it results in heterogeneous nucleation at the matrix surface. Hence, the formed contact is better. According to the results of UV-Vis and EEL spectroscopy, the contact between metallic and semiconducting nanoparticles results in the shift of the SPR peak position. The data on the photocatalytic activity and absorbance spectra of silver-contained composites demonstrate that the sample with lower photocatalytic activity has better contact because of Ohmic contacts between silver and matrices.
This work was supported by RFBR and M.V.Lomonosov Moscow State University Program of Development.

 

[511] CREATION OF NANO-PATTERNED POLYELECTROLYTE MULTILAYERS

 

Lior Asor1, Roy Shenhar2

1 The Hebrew University of Jerusalem; The Institute of Chemistry
2 The Hebrew University of Jerusalem; Givat Ram

Creation of Nano-patterned polyelectrolyte multilayers
Lior Asor & Roy Shenhar
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
Nanoscale, periodically patterned surfaces attract a considerable interest due to their wide applicability in a range of fields, such as optics (where a well-defined periodicity is crucial for wavelengths selection) and catalysis (where the nanoscale pattern gives rise to a high surface area). A well-defined, nanoscale pattern usually requires the creation of a distinguishable chemical contrast on the surface. To this day, however, such patterns are achieved mainly by electron-beam lithography, which is a very expensive and time consuming process.
In this work we present a non-lithographic solution for the creation of such patterns, using a combination of two self-assembly approaches: micro-phase separation of block copolymers and layer-by-layer deposition of polyelectrolytes. Block copolymers consist of two chemically distinct polymers joined together by a covalent bond. Upon annealing, these copolymers self-assemble into various ordered microstructures such as lamellae and cylinders, with periodicities on the 10-100 nm scale. Surface patterns displayed by block copolymers in thin films serve as templates for further nanoscale construction. The Layer-by-Layer (LbL) technique, which has become a leading approach for the assembly of polyelectrolyte multilayers using electrostatic interactions, can be used to create patterned multilayer arrays of controllable composition. The poster will discuss a thorough characterization of the assembly of patterned multilayers with a polyelectrolyte system that gives rise to non-linear growth.

 

[519] FABRICATION NANODIAMONDS BY LASER SYNTHESIS AND THEIR APPLICATIONS IN INDUSTRY AND MEDICINE

 

Olga Levinson1, Boris Zousman2

1 Ray Techniques Ltd. ; Nanodiamond Technologies
2 Ray Techniques Ltd.; Nanodiamond Technologies

Ray Techniques Ltd (RT) is the Israeli company established in 2009 and engaged in nanodiamond technologies, – manufacturing diamond nano-powder and suspensions by proprietary method and development of their applications in industry, science and medicine.
The developed technology consists of three levels:
 Nanodiamond fabrication – we mix ash with wax, treat the mixture with laser and obtain pure diamond nanocrystals (patent applications in USA, EU, Korea, Japan & Israel).
 Nanodiamond modification: we solve the problem of nanodiamond aggregation which restricts the growth of Global Market of this unique material; special surface treatment (know-how) enables to obtain stable suspensions without aggregates and sediments.
 Design final products: we exploit unique diamond features: highest hardness and wear resistance, highest thermal conductivity and electrical insulation, unique optical and electronic properties, biocompatibility, radiation and chemical resistance; the product list includes antifriction lubricants, coolants, fine polishes, delivery agent for cancer research, thermal grease and adhesive for electronics and other innovative products.
Presently, nanodiamonds are produced on an industrial scale by non-controlled hazardous detonation technology, which cannot provide constant quality and output. Also the absence of industrial technologies for uniform distribution of nanodiamonds in solvents does not enable their wide use in industry.
RT is looking for partners for commercialization of its technology and products. Industrial manufacturing of nanodiamond additives and implementation of the developed technology of laser nanodiamond synthesis will result in rapid increase in the Global Market of nanodiamond powder and compounds and will enable the solving of most serious problems in electronics, machinery, energy and bio-medicine.

 

[523] NANODIAMOND ADDITIVES FOR 3D PRINTING

 

Olga Levinson1, Boris Zousman2, Michael Farber2

1 Ray Techniques Ltd. ; Nanodiamond Technologies
2 Ray Techniques Ltd.; Nanodiamond Technologies

Here we present the results of investigation intended to check the possibility of use nanodiamonds as reinforcing filler in thermoplastics for 3D-printing. To do that we produced filaments from Acrylonitrile Butadiene Styrene (ABS) and from ABS modified with nanodiamonds (ABS-ND) by extrusion and compared the features of manufacturing process and mechanical properties of produced filaments.
ABS was chosen for this experiment as a common thermoplastic polymer widely used in machinery, electronics, household and medical appliances and construction. At last time ABS has become the main material for rapid prototyping by extrusion-based 3D printers. Currently the wide use of this technology is restricted by the high cost of filaments mainly caused by a low productivity of their manufacturing. Improvement of functional characteristics of ABS and reducing manufacturing costs is an actual issue for material engineering.
It was found that ABS modification with 0.05 wt.% specially functionalized nanodiamonds has resulted in significant decrease in extrusion friction enabling to enhance the productivity of filament manufacturing by minimum 50 %; herewith, rotation force reduced by 24 % which can lead to energy saving and prolonged durability of tools.
Use nanodiamond additive in amount of 0.05 wt.% enhanced tensile strength and load of break of ABS by ≈ 14.5 % while stiffness and elastic modulus increased by 22.5 %; wherein, filament prolongation at break reduced by 94 %.
It is expected, that ABS modification by nanodiamonds performed during ABS pellets manufacturing will result in much higher homogeneity of nanodiamond distribution in polymer and better improvement of mechanical and thermal properties.
The company is looking for partners interested in the development of nanodiamond additive to thermoplastics and implementation of nanodiamond technology in 3D printing. The potential market is huge. If only 1 % of currently produced ABS will be modified with 0.05 wt. % of nanodiamonds, 50 ton nanodiamonds annually is required for this application, amount highly increasing current nanodiamond powder Global Market.

 

[536] EPOXY NANOCOMPOSITES WITH MODIFIED CELLULOSE NANO CRYSTALS AS ADDITIVES

 

Eldho Abraham1, Oded Shoseyov1

1 The Harvey M. Krueger Family Center for Nanoscience and Nanotechnology; The Hebrew University of Jerusalem

Epoxy Nanocomposites with Modified Cellulose Nano Crystals as Additives
Eldho Abraham*and Oded Shoseyov*
*R.H. Smith Institute of Plant Sciences and Genetics and The Harvey M. Krueger Family Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Israel

ABSTRACT:
Epoxy nanocomposites composed of highly esterified cellulose nanocrystals (CNC) were prepared and discussed. CNCs which isolated from paper waste were modified with acetic anhydride by a novel method which resulted in highly esterified CNCs (ACNC). Suspensions of these ACNC crystals in acetone were combined with an epoxy (EPON 828) and the curing agent Epikure 3140 by solution mixing. Film casted nanocomposites were produced by a high temperature curing followed by a subsequent room temperature curing. The ACNC content was systematically varied between 0.01 and 1 wt. %. Electron microscopy studies suggest that the ACNC crystals are evenly dispersed within the epoxy matrix. Dynamic mechanical analysis revealed that the glass transition temperature (Tg) of the materials was not significantly influenced by the incorporation of the ACNC filler. The tensile storage moduli (E′) of the nanocomposites increased modestly between room temperature and 150°C, especially for ACNC concentration less than 1. The mechanical properties of the new materials are promised at low filler concentration (Fig.1) as a result of the formation of a percolating ACNC network in which stress transfer is facilitated by strong interactions between the ACNC crystals.

Keywords: epoxy resin, hydrophobic CNC, nanocomposite, percolating network

Fig.1. Tensile properties of ACNC reinforced epoxy nanocomposites

 

 

Grain growth kinetics in nano-sized Li-MgO·1.21Al2O3 spinel

Lee Shelly, Yuval Mordekovitz and Shmuel Hayun
Department of Materials Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O.Box 653, Beer-Sheva 84105, Israel

Grain growth in MgO·nAl2O3 spinel is strongly affected by its stoichiometric ratio, where for n≥1 spinel it is fairly limited comparing to samples with n <1. In order to overcome this difficulty the use of sintering additives was proposed, where the most common is LiF. Even though the effect of LiF on the sintering behavior of MgAl2O4 has been extensively studied, the effect of lithium on grain growth, remain unclear. In the current study the effect of lithium on the grain growth kinetics of non-stoichiometric, MgO·1.21Al2O3 spinel was investigated. Preliminary results show that the grain growth kinetics in nano-sized Li doped MgO·1.21Al2O3 is strongly dependent not only on the Li amount but also on the grain size. The relations between the grain size, lithium amount and grain growth kinetics in non-stoichiometric magnesium aluminate spinel will be discussed.

Keywords: Grain growth kinetics, MgO·nAl2O3 spinel, lithium.

 

Effect of lithium on thermal stability of nano-sized non-stoichiometric magnesium aluminate spinel

Yuval Mordekovitz and Shmuel Hayun
Department of Materials Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O.Box 653, Beer-Sheva 84105, Israel
Abstract
The use of LiF as a sintering additive for fabrication of transparent polycrystalline magnesium aluminate spinel has been widely discussed in the literature. In the present talk the thermal stability of Li-doped non-stoichiometric nano-sized magnesium aluminate spinel, synthesized using a combustion synthesis method was studied using XRD, FTIR, SEM and high temperature differential scanning calorimetry (DSC). It was found that the Li content within the magnesium aluminate spinel is a function of the crystallite size and stoichiometry. Moreover, the limited homogeneity range between LiAl5O8 and MgO·nAl2O3 spinel (n is the ratio between Al2O3 and MgO) found to increase with the reduction in crystallite size. Structural analysis using FTIR spectroscopy indicated that as-synthesized materials were heavily disordered. The effect of the Li on the surface and interfacial enthalpy are stoichiometry dependent (Figure 1), as well as the coarsening path. These dependencies will be discussed.

 

Measuring the Space Charge Potential in Nano-Sized Magnesium Aluminate Spinel Using Off-Axis Electron Holography

 

Mahdi Halabi1,2, Amit Kohn3 and Shmuel Hayun1,2
1. Department of Materials Engineering, 2. Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O.Box 653, Beer-Sheva 84105, Israel
3. Department of Materials Science and Engineering, Tel Aviv University, Ramat Aviv, Tel Aviv 6997801, Israel

Solute and point defects segregation to grain boundaries are fundamental phenomena in polycrystalline ionic materials [1,2]. Therefore, it is important to investigate the influence of this segregation adjacent to grain boundaries on the defect chemistry and space charged zone (SCZ) [3]. The classical approach for estimating the space charge potential (SCP) in ionic materials is based on defect concentration and formation energy using Boltzmann distribution [2,3]. These estimates are inaccurate because values of the defects formation energy are usually unknown. Additionally, assumptions used [2, 3] for distribution of charge carriers (defects) in SCZ correspond to semiconductors and not to ionic materials. Thus, more realistic models should be developed, for which experimental measurements of the SCZ are required. Here, the SCP is estimated in model systems of MgO·0.95Al2O3 and MgO·1.07Al2O3 spinel using off-axis electron holography (OAEH) [4]. Consequently, the relations between GB segregation (Fig. 1a), electrostatic potential (Fig. 1b) and heat treatment on the SCP are discussed.

Figure 1- a: Line profiles perpendicular to grain boundaries of cation concentration ratio (Mg to Al) as calculated from EELS measurements. b: Line profiles perpendicular to grain boundaries of the electrostatic potential of SCZ as calculated from OAEH measurements. Note: MgO∙nAl2O3 stoichiometric ratios, n=0.95 (red) and 1.07 (blue) heated at 1200°C by SPS

Reference List
[1] M. Rubat du Merac et al., J Am Ceram Soc. 96 (2013) 3341-3365.
[2] N. Nuns, F. Béclin et al., J Am Ceram Soc. 92 (2009) 870-875.
[3] Y. Chiang et al., J Am Ceram Soc. 73 (1990) 1153-1158.
[4] A. Pantzer et al., Ultramicroscopy 138 (2014) 36-45.

 

 

Metal/Metal Alloy Nanoparticles Catalytic Activity Towards the Reduction of 4-Nitrophenol with Sodium Borohydride

 

Shoval Gilboa1, Kirill Magidey1, Tomer Zidki2

1 Department of Chemical Engineering, Ariel University, Israel 2 Department of Biological Chemistry and Schlesinger Center for Compact Accelerators and Radiation Sources, Ariel University, Israel

 

Keywords: Metal alloys, Nanoparticles, Catalysis

Abstract

Nanoparticles (NPs) and in particular metal NPs are vastly studied owing to their properties in variety of fields such as: medicine, optics, electronics, catalysis, etc. Metal NPs are good catalysts as most of their atoms are low-coordinated surface atoms. These atoms are more active than the bulk atoms.

The catalytic reduction of 4-nitrophenol (4-Nip) is one of the most used reactions to test the catalytic activity of metal NPs in aqueous solution. This is due to these the ease of monitoring this reaction by UV-vis spectroscopy. The decrease in the strong absorption of 4-nitrophenolate ions at 400 nm can be readily monitored by UV-vis spectroscopy along with the rise of the 4-phenylamine peak at 300 nm. This reaction is suitable for testing the metal/metal alloy NPs catalytic activity. Due to its optical properties, the reaction of 4-Nip reduction is used as a prototype for catalysis on many metal NPs.

We are studying the catalytic effect of different metals (Au, Ag and Pt) and metal-alloys NPs on the reduction of 4-Nip by sodium borohydride. In this study we synthesize aqueous metal NPs suspensions by the precursor salts reduction with sodium borohydride. The metal alloys are synthesized similarly using a mixture of salts in the precursor solution.

The reactions are monitored using spectrophotometer following the increase of the 4-Nip signal at 400 nm and the increase of the 4-phenylamine signal at 300 nm.

Primary results indicate that:

1. The order of the metal NPs activity is: Pt < Ag < Au
2. The alloys NPs show much better activity than the individual metals towards the reduction of 4-Nip.
3. No induction time is observed for certain catalyst composition (in contrast to the literature) or the reaction is too fast to observe the induction time.
4. The best catalyst so far is the Ag-Pt alloy nanoparticle.

 

Plasma Treatment of MWINT-WS₂ for Synthesis of Single Wall Nanotubes of WS₂

 

Volker Brueser¹, Ronit Popovich Biro², Alla Zak³

¹Leibniz-Institute for Plasma Science and Technology, Germany, ²Weizmann Institute of Science, Israel, ³Holon Institute of Technology, Israel,

The synthesis of multiwall inorganic nanotubes of tungsten disulfide (INT-WS₂) in pure phase and large amounts was reported in 2009. The growth mechanism of this one-pot two-steps reaction of tungsten oxide with hydrogen and hydrogen sulfide, was carefully investigated.[1] The obtained nanotubes are 80-120 nm in diameter and 10-20 micron in length, exhibiting high degree of crystallinity and needle-like morphology.

Nanostructures formed of monomolecular layer attract increasing attention of the scientific community during the last few decades. Among these materials are carbon fullerenes, like C₆₀, single wall carbon nanotubes (SWCNT), graphene and lately monomolecular layers of inorganic transition metal chalcogenides, named 2D-materials. Here, we reported the synthesis of single- to triple-wall WS₂ nanotubes (SWINT-WS₂) with a diameter of 3–7 nm and a length of 20–100 nm which were produced by radio frequency plasma treatment of multiwall INT-WS₂.[2]

Due to their high elastic energy of folding the WS₂ nanotubes become less stable, as the radius of curvature shrinks, rendering their synthesis more difficult. Indeed, theoretical calculations have shown that the energy-per-atom increases with a decreasing number of atoms, diameter and number of layers for the WS₂ (MoS₂) nanotubes. Therefore, generation of the nanotubes of a small size and single layer requires highly exergonic conditions. The developed process for high-power radio frequency plasma irradiation of multiwall INT-WS₂ meets these requirements. Moreover, the elastic strain stored in the bent layers of large multiwall nanotubes plays a crucial role in this process, providing an extra stimulus for the SWINT formation.

Careful investigation of the plasma-reactor parameters enables us to further improve the synthesis of single-to-triple wall nanotubes. The majority of the nanotubes obtained under the improved conditions are single walled nanotubes of WS₂. Additional work is required in order to scale-up the production of SWINT-WS₂ and to control their aspect ratio.

The large surface area/volume ratio of SWINT-WS₂ and their semiconductor nature can yield interesting chemical properties, making them suitable for numerous energy storage devices, catalytic applications, hydrogen storage and optoelectronic applications.

References

[1] A. Zak, L. Sallacan-Ecker, A. Margolin, Y. Feldman, R. Popovitz-Biro, A. Albu-Yaron, M. Genut and R. Tenne, Scaling-Up of the WS2 Nanotubes Synthesis,  Fullerene, Nanotubes,  Carbon Nanostruct. 19, 18-26 (2011).

[2] V. Brüser, R Popovitz-Biro, A Albu-Yaron, T Lorenz, G Seifert, R Tenne, and A Zak. “Single- to Triple-Wall WS₂ Nanotubes Obtained by High-Power Plasma Ablation of WS₂ Multiwall Nanotubes.” Inorganics 2, no. 2 (2014): 177-90.

 

Characterization of nanometric type II superlattice layers for near- room temperature extended short-wave infrared detection.

 

1. Uliel^1,2, D. Cohen-Elias¹, N. Sicron¹, Y. Paltiel², M. Katz¹

¹ Solid State Physics Department, Applied Physics Division, Soreq NRC, Yavne, Israel
² Applied Physics Department, Hebrew University, Jerusalem, Israel

Extended Short Wave Infra-Red (E-SWIR, 1.7-2.5-mm) photodetectors are required for several defense and civil industry applications. Existing E-SWIR high responsivity detector technology can be divided into two groups, unmatched InGaAs/InP layers, and MCT layers .        

Unmatched InGaAs/ InP layer devices exhibit low operability in Focal Plane Arrays (FPA) due to the large concentration of defects originating in the lattice mismatch. MCT layer devices are expensive and suffer from very low yield. Therefore, there is a need for high quality near room-temperature E-SWIR detectors.

The work presented here focuses on a nanometric Type- Two Super Lattice (T2SL) structure, based on interleaving nano-layers of InGaAs and GaAsSb, grown by MBE process on an InP substrate. These layers were recently proposed as a candidate for near room temperature E-SWIR detection. The quantum confinement effect within the nano-layers allows for bandgap engineering of a new artificial material.

Material characterization, quantum simulation, and device fabrication is presented.

The described structure is adjusted for ~2.35mm detection. The devices fabricated are PIN photodiodes formed by selective diffusion of Zinc. The results show promising high- quantum efficiency E-SWIR detection, while exhibiting relatively low dark currents.

 

 

Mechanistic Insights into Crystallization of Perylene diimide Based Organic Nanocrystals in Aqueous Media.

 

Yael Tsarfati, Shaked Rosenne, Raja Bhaskar Kanth, Haim Weissman,

and Boris Rybtchinski.

 

Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel

 

Supramolecular synthesis allows us a facile fabrication of a wide variety of complex systems from simple molecular precursors. However, understanding of the mechanism of formation, specifically, the transition from solution based molecular recognition into practical solid state nanocrystals has been found to be extremely challenging. Many studies are attempting to achieve insights into the crystallization mechanism, including our own lab.^{1, 2}

 

In this contribution, we present our developing perspective and methodology to target the study of early stage crystallization in organic crystals encapsulating one or two component systems. Our molecular crystals are based on representative simple aromatic compounds – Perylene diimide (PDI) derivatives. These PDI-based electron donors and acceptors are extensively studied in the context of molecular self-assemblies due to their excellent optical and electronic properties that also render them applicable in the fields of solar cells and nano-electronics. Such molecules often assemble into needles-like nanocrystals, depending on their solubility in water and their functional groups. The crystallization evolution is monitored using electron microscopy, including cryo-TEM, and optical spectroscopy to gather experimental data on the intermediate stages and products of crystallization. The results reveal interesting insights both into crystallization in general and into PDI-based co-crystals in particular. We hope that our study will shed light on nucleation and growth mechanisms and increase our control on the processes and products of crystallization. 

 

References

 

(1)      Vekilov, P. G. Nucleation. Cryst. Growth Des. 2010, 10, 5007–5019.

(2)      De Yoreo, J. J.; Gilbert, P. U. P. a.; Sommerdijk, N. a. J. M.; Penn, R. L.; Whitelam, S.; Joester, D.; Zhang, H.; Rimer, J. D.; Navrotsky, A.; Banfield, J. F.; Wallace,  a. F.; Michel, F. M.; Meldrum, F. C.; Colfen, H.; Dove, P. M. Crystallization by particle attachment in synthetic, biogenic, and geologic environments. Science. 2015, 349, aaa6760–aaa6760.

 

 

GaInAs and InGaAsP Based Photovoltaic Absorber Materials for
Optical Power Transmission in the 980 and 1310 nm Range

 

Henning Helmers^#, David Lackner, Paul Beutel, Jens Ohlmann, Simon P. Philipps, Frank Dimroth,
Andreas W. Bett

Fraunhofer Institute for Solar Energy Systems ISE, Freiburg, Germany

 

Key Words: III-V, nano materials, power-by-light, semiconductors

Optical power transmission is an emerging technology and enables various remote applications where conventional power supply over copper wire is challenging or even impossible. To power remote electronics by light, three main components are required: a light source (laser), an optical connection (optical fiber or free space transmission), and an opto-electronic converter (photovoltaic cell). Advantages of power-by-light technology include inherent galvanic isolation, electromagnetic compatibility, and the possibility for wireless power transmission.

III-V compound semiconductors (Figure 1) are used to realize high-efficient photovoltaic laser power converters. For optimal system efficiency, the absorber bandgap has to be tuned to match the laser wavelength. This way, thermalization losses (as a major loss mechanism in solar cells) practically vanish. In this work, we report on progress on GaInAs and InGaAsP absorber materials, optimized for wavelengths around 980 nm and 1310 nm, respectively. The materials are grown epitaxially by MOVPE. The Ga_0.85In_0.15As material system is grown metamorphically on a GaAs substrate, the InGaAsP material system is deposited lattice-matched on an InP substrate.

 

Figure 1: Plot of bandgap and corresponding wavelength of III-V materials over the lattice constant of the respective compound semiconductors.

 

 

 

New Horizons in Structural and Chemical Nanocharacterization of Carbon Based Nanotubes and Graphene

 

Hybrid microscopic technologies have great potential for developing new directions of combined structural and chemical nanocharacterization.  In order for the full utilization of such tools there has to be a unique architecture.  In the case of Raman spectroscopic chemical characterization combined with atomic force microscopy (AFM) both the instrument and the probe design have to be transparently integrated for fully accessing the application potential of this combined tool. In this paper three singular developments will be highlighted.  The first is an AFM instrument that is completely compatible with any optical microscope.  The second is a AFM probe that is transparent and totally non-interfering with the Raman measurement and the third is a measurement of force that has extreme sensitivity down to 1.6pN.  This is in the realm of such techniques as optical tweezers and allows for the sensitivity of optical tweezers without a liquid environment. The applications of such an instrument to the interesting problem of functional imaging in new carbon based materials will be discussed within the context of single walled carbon nanotubes and 2D materials including graphene.  The force sensitivity of the instrument will be described and the ability of the combined tool to functionally follow with AFM based techniques both structural and functional changes will be presented.

 

 

Summary   Title New Horizons in Structural and Chemical Nanocharacterization of Carbon Based Nanotubes and Graphene Category Nanomaterials Presentation type Poster Presentation Submitter Dr. John Parthenios, FORTH/ ICE-HT, Patras, Greece   Speaker Dr. John Parthenios, FORTH/ ICE-HT, Patras, Greece   Main author Dr. John Parthenios, FORTH/ ICE-HT, Patras, Greece Authors Dr. John Parthenios1   Prof. Aaron Lewis 2   1 FORTH/ ICE-HT, Patras, Greece  2 Hebrew University of Jerusalem; Applied Physics, Jerusalem, Israel & Nanonics Imaging Ltd., Jerusalem, Israel