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Structural And Catalytic Differences In The Effect Of Co And Mo As Promoters For Pt-Based Aqueous Phase Reforming Catalysts, Paul J. Dietrich, Fred G. Sollberger, M. Cem Akatay, Eric A. Stach, W.Nicholas Delgass, Jeffrey T. Miller, Fabio H. Ribeiro 2014 Purdue University

Structural And Catalytic Differences In The Effect Of Co And Mo As Promoters For Pt-Based Aqueous Phase Reforming Catalysts, Paul J. Dietrich, Fred G. Sollberger, M. Cem Akatay, Eric A. Stach, W.Nicholas Delgass, Jeffrey T. Miller, Fabio H. Ribeiro

Birck and NCN Publications

Reaction rates (site time yields, normalized to CO chemisorption sites) and product selectivity were determined for PtCo, PtMo, and Pt supported on multi-walled carbon nanotubes for aqueous phase reforming of glycerol. The bimetallic PtCo and PtMo catalysts had 4.6x and 5.4x higher glycerol consumption rates than Pt, and 3.9x and 0.6x rates in H-2 formation compared to Pt. Hydrogen generation selectivity was similar on Pt and PtCo, but PtMo had an increase in selectivity to C-O cleavage products, which reduced H-2 yield at conversions over 60% (85-90% hydrogen yield for Pt and PtCo, 65% for PtMo ...


Size-Dependent Electroelastic Properties Of Piezoelectric Nanoplates, Zhengrong Zhang 2014 Western University

Size-Dependent Electroelastic Properties Of Piezoelectric Nanoplates, Zhengrong Zhang

University of Western Ontario - Electronic Thesis and Dissertation Repository

With the development of nanotechnology, piezoelectric nanostructures have attracted a surge of interests in research communities for the potential applications as transistors, sensors, actuators, resonators and energy harvesters in nanoelectromechanical systems (NEMS) due to their high electromechanical coupling and unique features at the nano-scale. Piezoelectric nanomaterials have been characterized to possess size-dependent electromechanical coupling properties from both experimental and theoretical perspectives. Therefore it is of great importance to investigate the physical mechanisms of these distinct nano-scale structure features in order to fulfill the design and application of those piezoelectricity-based nanodevices.

Due to large surface to volume ratio and manifest strain ...


Surfactant Assisted Dispersion Of Single-Walled Carbon Nanotubes In Polyvinylpyrrolidone Solutions, Tennison Yu 2014 Western University

Surfactant Assisted Dispersion Of Single-Walled Carbon Nanotubes In Polyvinylpyrrolidone Solutions, Tennison Yu

University of Western Ontario - Electronic Thesis and Dissertation Repository

Obtaining stable aqueous dispersions is one of the main challenges hindering a widespread and effective use of single-walled carbon nanotubes (SWNT) in many applications. Although it has been recognized that their versatility makes them an extremely attractive material, the unique molecular structure that gives SWNTs their unmatched electronic, mechanical, and thermal properties is also responsible for strong van der Waals interactions. This, combined with extremely high aspect ratios and flexibility, causes SWNTs to adhere strongly into tightly bundled ropes. In these bundles, SWNTs are not as useful as their linearized unbundled equivalents. Thus, in order to take advantage of their ...


Au@Tio2 Nanocomposites For The Catalytic Degradation Of Methyl Orange And Methylene Blue: An Electron Relay Effect, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho 2014 SelectedWorks

Au@Tio2 Nanocomposites For The Catalytic Degradation Of Methyl Orange And Methylene Blue: An Electron Relay Effect, Mohammad Mansoob Khan Dr, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Au@TiO2 nanocomposites were used for the catalytic degradation of methyl orange and methylene blue by NaBH4. A detail pathway for step by step reduction, oxidation and complete mineralization of intermediates into the respective end-products was established by UV-vis spectroscopy, chemical oxygen demand, ion chromatography and cyclic voltammetry (CV). CV studies confirmed that the dyes were reduced and oxidized to the end-products by NaBH4 in the presence of Au@TiO2 nanocomposites and O2•, •OH and HO2• radicals generated in-situ. Results suggest that Au@TiO2 nanocomposites not only assist in the decolorization of dyes, but also promote their complete mineralization into ...


Highly Visible Light Active Ag@Zno Nanocomposites Synthesized By Gel-Combustion Route, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho 2014 SelectedWorks

Highly Visible Light Active Ag@Zno Nanocomposites Synthesized By Gel-Combustion Route, Mohammad Mansoob Khan Dr, S. A. Ansari, J. Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Highly visible light active 1% and 3% Ag@ZnO nanocomposites were synthesized via a gel combustion route using citric acid as a fuel. The formation of the nanocomposites with enhanced properties was confirmed using a range of characterization techniques, photocatalysis and photoelectrochemical studies. Compared to the pristine ZnO nanoparticles, the Ag@ZnO nanocomposites exhibited enhanced visible light photocatalytic activity for the degradation of methylene blue and photoelectrochemical response. A mechanism was proposed to account for the photocatalytic activities of the Ag@ZnO nanocomposite that showed the surface plasmon resonance (SPR) of Ag is an effective way of enhancing the visible ...


Topological Insulator Based Spin Valve Devices: Evidence For Spin Polarized Transport Of Spin-Momentum-Locked Topological Surface States, Jifa Tian, Isaac Childres, Helin Cao, Tian Shen, Ireneusz Miotkowski, Yong P. Chen 2014 Purdue University

Topological Insulator Based Spin Valve Devices: Evidence For Spin Polarized Transport Of Spin-Momentum-Locked Topological Surface States, Jifa Tian, Isaac Childres, Helin Cao, Tian Shen, Ireneusz Miotkowski, Yong P. Chen

Birck and NCN Publications

Spin-momentum helical locking is one of the most important properties of the nontrivial topological surface states (TSS) in 3D topological insulators (TIs). It underlies the iconic topological protection (suppressing elastic backscattering) of TSS and is foundational to many exotic physics (e.g., majorana fermions) and device applications (e.g., spintronics) predicted for TIs. Based on this spin-momentum locking, a current flowing on the surface of a TI would be spin-polarized in a characteristic in-plane direction perpendicular to the current, and the spin-polarization would reverse when the current direction reverses. Observing such a spin-helical current in transport measurements is a major ...


Thermoelectric Topping Cycles For Power Plants To Eliminate Cooling Water Consumption, Kazuaki Yazawa, Menglong Hao, Bin Wu, Armin K. Silaen, Chenn Qian Zhou, Timothy Fisher, Ali Shakouri 2014 Purdue University

Thermoelectric Topping Cycles For Power Plants To Eliminate Cooling Water Consumption, Kazuaki Yazawa, Menglong Hao, Bin Wu, Armin K. Silaen, Chenn Qian Zhou, Timothy Fisher, Ali Shakouri

Birck and NCN Publications

This work shows that thermoelectric (TE) topping generators can add 4-6% to the overall system efficiency for advanced supercritical steam turbines (Rankine cycle) that nominally generate power with 40-42% efficiency. The analysis then considers how this incremental topping energy can replace cooling water flow with air-cooled condensers (ACC) while maintaining current power output and plant efficiency levels with commensurate economic benefit ($/kW h). The simulated TE modules are located inside a coal-fired boiler wall constructed of wet steam tubes. The topping TE generator employs nontoxic and readily available materials with a realistic figure-of-merit range (ZT = 0.5-1.0). Detailed heat ...


A Systematic Study Of The Process-Structure Relationship For Building Polymer Interphase Regions In Carbon Nanotube Composites, Yiying Zhang 2014 Northeastern University

A Systematic Study Of The Process-Structure Relationship For Building Polymer Interphase Regions In Carbon Nanotube Composites, Yiying Zhang

Mechanical Engineering Dissertations

As the world's demands for new high-performance materials continuously grow, reinforcing polymer materials with carbon nanotubes (CNT) to produce lightweight composites with high properties has been pursued since their discovery. However, to date composites with the anticipated superior properties have not been achieved yet. This is mainly due to the lack of fundamental understanding regarding processing these materials as well as manipulating the nano-scale assemblies, which would dictate the desired macroscopic performance.

This dissertation work focuses on understanding the development of interfacial zones in polymer/CNT composites, which is necessary for producing mechanically outstanding composite materials. Highly crystalline and ...


Opto-Electronic Devices With Nanoparticles And Their Assemblies, Chieu Van Nguyen 2014 University of Nebraska - Lincoln

Opto-Electronic Devices With Nanoparticles And Their Assemblies, Chieu Van Nguyen

Chemical & Biomolecular Engineering Theses, Dissertations, & Student Research

Nanotechnology is a fast growing field; engineering matters at the nano-meter scale. A key nanomaterial is nanoparticles (NPs). These sub-wavelength (< 100nm) particles provide tremendous possibilities due to their unique electrical, optical, and mechanical properties. Plethora of NPs with various chemical composition, size and shape has been synthesized. Clever designs of sub-wavelength structures enable observation of unusual properties of materials, and have led to new areas of research such as metamaterials. This dissertation describes two self-assemblies of gold nanoparticles, leading to an ultra-soft thin film and multi-functional single electron device at room temperature. First, the layer-by-layer self-assembly of 10nm Au nanoparticles and polyelectrolytes is shown to behave like a cellular-foam with modulus below 100 kPa. As a result, the composite thin film (~ 100nm) is 5 orders of magnitude softer than an equally thin typical polymer film. The thin film can be compressed reversibly to 60% strain. The extraordinarily low modulus and high compressibility are advantageous in pressure sensing applications. The unique mechanical properties of the composite film lead to development of an ultra-sensitive tactile imaging device capable of screening for breast cancer. On par with human finger sensitivity, the tactile device can detect a 5mm imbedded object up to 20mm below the surface with low background noise. The second device is based on a one-dimensional (1-D) self-directed self-assembly of Au NPs mediated by dielectric materials. Depending on the coverage density of the Au NPs assembly deposited on the device, electronic emission was observed at ultra-low bias of 40V, leading to low-power plasma generation in air at atmospheric pressure. Light emitted from the plasma is apparent to the naked eyes. Similarly, 1-D self-assembly of Au NPs mediated by iron oxide was fabricated and exhibits ferro-magnetic behavior. The multi-functional 1-D self-assembly of Au NPs has great potential in modern electronics such as solid state lighting, plasma-based nanoelectronics, and memory devices.

Adviser: Ravi F. Saraf


Tunable Landau-Zener Transitions In A Spin-Orbit-Coupled Bose-Einstein Condensate, Abraham J. Olson, Su-Ju Wang, Robert J. Niffenegger, Chuan-Hsun Li, Chris H. Greene, Yong P. Chen 2014 Purdue University

Tunable Landau-Zener Transitions In A Spin-Orbit-Coupled Bose-Einstein Condensate, Abraham J. Olson, Su-Ju Wang, Robert J. Niffenegger, Chuan-Hsun Li, Chris H. Greene, Yong P. Chen

Birck and NCN Publications

The Landau-Zener (LZ) transition is one of the most fundamental phenomena in quantum dynamics. It describes nonadiabatic transitions between quantum states near an avoided crossing that can occur in diverse physical systems. Here we report experimental measurements and tuning of LZ transitions between the dressed eigenlevels of a Bose-Einstein condensate (BEC) that is synthetically spin-orbit (SO) coupled. We measure the transition probability as the BEC is accelerated through the SO avoided crossing and study its dependence on the coupling between the diabatic (bare) states, eigenlevel slope, and eigenstate velocity-the three parameters of the LZ model that are independently controlled in ...


In-Situ Fluorescent Immunomagnetic Multiplex Detection Of Foodborne Pathogens In Very Low Numbers, Il-Hoon Cho, Lisa Mauer, Joseph Irudayaraj 2014 Purdue University

In-Situ Fluorescent Immunomagnetic Multiplex Detection Of Foodborne Pathogens In Very Low Numbers, Il-Hoon Cho, Lisa Mauer, Joseph Irudayaraj

Birck and NCN Publications

Consumption of foods contaminated with pathogenic bacteria is a major public health concern. Foods contain microorganisms, the overwhelming majority of which are nonpathogenic, some are responsible for food spoilage, and some cause serious illness leading to death or a variety of diseases in humans. The key challenge in food safety is to rapidly screen foods to determine the presence of pathogens so that appropriate intervention protocols can be pursued. A simple fluorometric immunological method in combination with a magnetic concentration step was developed for rapid detection of target bacteria with high sensitivity and specificity in less than 2 h without ...


Photonic-Band-Gap Engineering For Volume Plasmon Polaritons In Multiscale Multilayer Hyperbolic Metamaterials, Sergei V. Zhukovsky, Alexey A. Orlov, Viktoriia E. Babicheva, Andrei V. Lavrinenko, J. E. Sipe 2014 Purdue University

Photonic-Band-Gap Engineering For Volume Plasmon Polaritons In Multiscale Multilayer Hyperbolic Metamaterials, Sergei V. Zhukovsky, Alexey A. Orlov, Viktoriia E. Babicheva, Andrei V. Lavrinenko, J. E. Sipe

Birck and NCN Publications

We study theoretically the propagation of large-wave-vector waves (volume plasmon polaritons) in multilayer hyperbolic metamaterials with two levels of structuring. We show that when the parameters of a subwavelength metal-dielectric multilayer (substructure) are modulated (superstructured) on a larger, wavelength scale, the propagation of volume plasmon polaritons in the resulting multiscale hyperbolic metamaterials is subject to photonic-band-gap phenomena. A great degree of control over such plasmons can be exerted by varying the superstructure geometry. When this geometry is periodic, stop bands due to Bragg reflection form within the volume plasmonic band. When a cavity layer is introduced in an otherwise periodic ...


Electronic Transport In Ingaas/Al2o3 Nfinfets, Shengwei Li, Yaodong Hu, Yangqing Wu, Daming Huang, Peide D. Ye, Ming-Fu Li 2014 Purdue University

Electronic Transport In Ingaas/Al2o3 Nfinfets, Shengwei Li, Yaodong Hu, Yangqing Wu, Daming Huang, Peide D. Ye, Ming-Fu Li

Birck and NCN Publications

Based on the multiple subbands quasi-ballistic transport theory, we investigate the electronic transport of nano size In0.53Ga0.47As nFinFETs with Al2O3 gate dielectric, emphasizing the saturation current region. 1D mobile charge density and gate capacitance density are introduced for the first time to describe the nano-FinFET transport property under volume inversion. With the extracted effective channel mobility of electrons in the linear region from our experiments, the electron mean free path. in the channel with the value of 5-9 nm is obtained. With only one fitting parameter alpha = 0.31 for the critical length l = L(kT/q/v ...


The Effect Of Dielectric Capping On Few-Layer Phosphorene Transistors: Tuning The Schottky Barrier Heights, Han Liu, Adam T. Neal, Mengwei Si, Yuchen Du, Peide D. Ye 2014 Purdue University

The Effect Of Dielectric Capping On Few-Layer Phosphorene Transistors: Tuning The Schottky Barrier Heights, Han Liu, Adam T. Neal, Mengwei Si, Yuchen Du, Peide D. Ye

Birck and NCN Publications

Phosphorene is a unique single elemental semiconductor with two-dimensional layered structures. In this letter, we study the transistor behavior on mechanically exfoliated few-layer phosphorene with the top-gate. We achieve a high ON-current of 144 mA/mm and hole mobility of 95.6 cm(2)/V.s.. We deposit Al2O3 by atomic layer deposition (ALD) and study the effects of dielectric capping. We observe that the polarity of the transistors alternated from p-type to ambipolar with Al2O3 grown on the top. We attribute this transition to the changes for the effective Schottky barrier heights for both electrons and holes at the ...


Quantifying The Local Density Of Optical States Of Nanorods By Fluorescence Lifetime Imaging, Jingjing Liu, Xunpeng Jiang, Satoshi Ishii, V. M. Shalaev, Joseph Irudayaraj 2014 Purdue University

Quantifying The Local Density Of Optical States Of Nanorods By Fluorescence Lifetime Imaging, Jingjing Liu, Xunpeng Jiang, Satoshi Ishii, V. M. Shalaev, Joseph Irudayaraj

Birck and NCN Publications

In this paper, we demonstrate a facile far-field approach to quantify the near-field local density of optical states (LDOS) of a nanorod using CdTe quantum dot (QD) emitters tethered to the surface of the nanorods as beacons for optical readouts. The radiative decay rate was extracted to quantify the LDOS; our analysis indicates that the LDOS of the nanorod enhances both the radiative and nonradiative decay of QDs, particularly the radiative decay of QDs at the end of a nanorod is enhanced by 1.17 times greater than that at the waist, while the nonradiative decay was enhanced uniformly over ...


Role Of Strain On Electronic And Mechanical Response Of Semiconducting Transition-Metal Dichalcogenide Monolayers: An Ab-Initio Study, David M. Guzman, Alejandro Strachan 2014 Purdue University

Role Of Strain On Electronic And Mechanical Response Of Semiconducting Transition-Metal Dichalcogenide Monolayers: An Ab-Initio Study, David M. Guzman, Alejandro Strachan

Birck and NCN Publications

We characterize the electronic structure and elasticity of monolayer transition-metal dichalcogenides MX2 (M = Mo, W, Sn, Hf and X = S, Se, Te) based on 2H and 1T structures using fully relativistic first principles calculations based on density functional theory. We focus on the role of strain on the band structure and band alignment across the series of materials. We find that strain has a significant effect on the band gap; a biaxial strain of 1% decreases the band gap in the 2H structures, by as a much as 0.2 eV in MoS2 and WS2, while increasing it for the ...


Computational Study Of Heterojunction Graphene Nanoribbon Tunneling Transistors With P-D Orbital Tight-Binding Method, Sung Geun Kim, Mathieu Luisier, Timothy B. Boykin, Gerhard Klimeck 2014 Purdue University

Computational Study Of Heterojunction Graphene Nanoribbon Tunneling Transistors With P-D Orbital Tight-Binding Method, Sung Geun Kim, Mathieu Luisier, Timothy B. Boykin, Gerhard Klimeck

Birck and NCN Publications

The graphene nanoribbon (GNR) tunneling field effect transistor (TFET) has been a promising candidate for a future low power logic device due to its sub-60 mV/dec subthreshold characteristic and its superior gate control on the channel electrons due to its one-dimensional nature. Even though many theoretical studies have been carried out, it is not clear that GNR TFETs would outperform conventional silicon metal oxide semiconductor field effect transistors (MOSFETs). With rigorous atomistic simulations using the p/d orbital tight-binding model, this study focuses on the optimization of GNR TFETs by tuning the doping density and the size of GNRs ...


Ultrafast And Scalable Laser Liquid Synthesis Of Tin Oxide Nanotubes And Its Application In Lithium Ion Batteries, Zhikun Liu, Zeyuan Cao, Biwei Deng, Yuefeng Wang, Jiayi Shao, Prashant Kumar, C. Richard Liu, Bingqing Wei, Gary Cheng 2014 Purdue University

Ultrafast And Scalable Laser Liquid Synthesis Of Tin Oxide Nanotubes And Its Application In Lithium Ion Batteries, Zhikun Liu, Zeyuan Cao, Biwei Deng, Yuefeng Wang, Jiayi Shao, Prashant Kumar, C. Richard Liu, Bingqing Wei, Gary Cheng

Birck and NCN Publications

Laser-induced photo-chemical synthesis of SnO2 nanotubes has been demonstrated by employing a nanoporous polycarbonate membrane as a template. The SnO2 nanotube diameter can be controlled by the nanoporous template while the nanotube length can be tuned by laser parameters and reaction duration. The microstructure characterization of the nanotubes indicates that they consist of mesoporous structures with sub 5 nm size nanocrystals connected by the twinning structure. The application of SnO2 nanotubes as an anode material in lithium ion batteries has also been explored, and they exhibited high capacity and excellent cyclic stability. The laser based emerging technique for scalable production ...


Surface Topography And Chemistry Shape Cellular Behavior On Wide Band-Gap Semiconductors, Lauren E. Bain, Ramon Collazo, Shu-han Hsu, Nicole Pfiester Latham, Michael J. Manfra, Albena Ivanisevic 2014 Purdue University

Surface Topography And Chemistry Shape Cellular Behavior On Wide Band-Gap Semiconductors, Lauren E. Bain, Ramon Collazo, Shu-Han Hsu, Nicole Pfiester Latham, Michael J. Manfra, Albena Ivanisevic

Birck and NCN Publications

The chemical stability and electrical properties of gallium nitride make it a promising material for the development of biocompatible electronics, a range of devices including biosensors as well as interfaces for probing and controlling cellular growth and signaling. To improve the interface formed between the probe material and the cell or biosystem, surface topography and chemistry can be applied to modify the ways in which the device interacts with its environment. PC12 cells are cultured on as-grown planar, unidirectionally polished, etched nanoporous and nanowire GaN surfaces with and without a physi-sorbed peptide sequence that promotes cell adhesion. While cells demonstrate ...


Technique For Quantitative Mapping Of Three-Dimensional Liquid-Gas Phase Boundaries In Microchannel Flows, Ravi S. Patel, Suresh V. Garimella 2014 Purdue University

Technique For Quantitative Mapping Of Three-Dimensional Liquid-Gas Phase Boundaries In Microchannel Flows, Ravi S. Patel, Suresh V. Garimella

Birck and NCN Publications

A diagnostic technique capable of characterizing interfaces between transparent, immiscible fluids is developed and demonstrated by investigating the morphology of liquid-gas interfaces in an adiabatic two-phase flow through a microchannel of 500 mu m x 500 mu m square cross section. Water seeded with 0.5 mu m-diameter fluorescent polystyrene particles is pumped through the channel, and the desired adiabatic two-phase flow regime is achieved through controlled air injection. The diagnostic technique relies on obtaining particle position data through epifluorescent imaging of the flow at excitation and emission wavelengths of 532 nm and 620 nm, respectively. The particle position data ...


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