Materials Science and Engineering Commons^™

Preparation And Characterization Of Carbon Supported Pd-Sb Composite Nanocatalysts For Formic Acid Electrooxidation, Long-Long Wang, Xiao-Lu Cao, Ya-Jun Wang, Jin-Hao Ping, Qiao-Xia Li

Journal of Electrochemistry

Palladium is considered as an efficient anode catalyst with high catalytic activity for electrooxidation of formic acid. To further improve the catalytic activity and stability, alloying or surface modification with Sb is an effective way. In this work, the well dispersed carbon supported Pd-Sb composite nanocatalysts (Pd-Sb/C) were synthesized by traditional impregnation reduction method with trisodium citrate as the complexing agent, sodium borohydride as the reducing agent. The morphologies of Pd-Sb/C and the effects of molar ratio of Pd to Sb on the electrocatalytic properties of Pd-Sb/C for HCOOH electrooxidation were studied. The XRD and XPS analyses on the as-prepared …

Effect Of Carbon Nanotubes On Anodic Properties Of Ti/Ru-Ir-Sn Oxides, Feng Lian, Yong-Lei Xin, Bo-Jiang Ma, Li-Kun Xu

Journal of Electrochemistry

The Ru-Ir-Sn metal oxide anodes coated on titanium (Ti/Ru-Ir-Sn) were prepared by thermal decomposition. The effects of amounts of carbon naotubes (CNTs) on anodic properties were studied by TGA, SEM, EDS, cyclic voltammetry, EIS, polarization measurements and accelerated life test. The thermogravimetric analysis and EDS spectrum data showed that the high temperature oxidation decomposition of CNTs did not take place under the condition of the sintering temperature of 470 ℃, and the CNTS still existed in the anode coating in an element form. Compared with the contrast samples, the surface crack of the coating increased, but remained typical morphology. Adding …

Fracture Mechanics-Based Simulation Of Pv Module Delamination, Dominic I. Jarecki, Johanna B. Palsdottir, Peter Bermel, Marisol Koslowski

The Summer Undergraduate Research Fellowship (SURF) Symposium

Photovoltaic (PV) cells are rapidly growing as a renewable alternative to fossil fuels like coal, oil, and natural gas. However, greater adoption has also reduced government subsidies, placing the onus of making solar panels economically competitive on innovative research. While multiple methods have been considered for reducing costs, with each reduction in cost comes the associated peril of reduction in quality and useful lifetime. Several problems considered solved have now resurfaced as potential failure mechanisms with the introduction of cheaper PV cell technologies. However, to remain economically viable, PV modules will not only have to become cheaper, they will have …

Nanomechanics Simulation Toolkit - Dislocations Make Or Break Materials, Michael N. Sakano, Alejandro Strachan, David Johnson, Mitchell Wood

The Summer Undergraduate Research Fellowship (SURF) Symposium

The goal of computational material science is to improve existing materials and design new ones through mathematical calculations. In particular, molecular dynamic simulations can allow for visualization of dislocations in a material, along with its resulting behavior when under stress. For example, plastic deformation and strain hardening result from the movement, multiplication and interaction of dislocations within the crystal structure. A simulation tool to study these phenomena was developed for the nanoHUB web resource as a part of the Network for Computational Nanotechnology at Purdue University and targets audiences ranging from undergraduate students to researchers. We created a user-friendly environment …

Wet Chemical Synthesis And Characterization Of Nanomaterials For Solar Cell Applications, Krystle N. Sy, Ramprasad Gandhiraman, Jessica E. Koehne

STAR Program Research Presentations

During long term space missions, it is necessary to have a reliable source of energy. Solar cells are an easy and reliable way to convert energy from the sun to electrical energy. NASA has used solar cells manufactured on Earth as an energy source for many of its missions. In order to develop technologies that will enable high efficiency solar cells, we are synthesizing nanostructured materials. A range of nanostructured materials, such as titanium dioxide nanowires, nickel nanoparticles, copper nanoparticles, and silver nanoparticles/nanowires, are synthesized. In this work, we are reporting on the synthesis of these nanomaterials and the electron …

Spotlight On Graphene Research From The Middle East, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

In an extension to the 2011 article “Reviews of Science for Science Librarians: Graphene” (Lehman 2011), this paper seeks to continue exploring the trend of graphene research but limits its focus to the research production of countries in the Middle East. In addition to reporting on the research output of this group of countries, this article will also examine the most prolific Middle Eastern graphene authors,their supporting institutions and funding agencies, the most cited publications from this group, the journals most used for publication of their work, and the general trend in graphene research growth in the Middle East. As …

Minimizing Sheet Resistance Of Organic Photovoltaic Cell Top Contact Electrode Layer: Silver Nanowire Concentration Vs. Conductive Polymer Doping Concentration, Caitlyn Cook

Materials Engineering

The top contact electrode layers of nine organic photovoltaic cells were prepared with two varying factors: three Silver nanowire (AgNW) densities deposited on a conductive polymer doped with three concentrations. Silver’s low sheet resistance of 20-Ω/sq is hypothesized to lower the sheet resistance of the anode layer and thus enhance the overall efficiency of the cell. Four-point probe measurements indicated that increasing AgNW density in the top contact electrode layer of an organic photovoltaic cell significantly reduces sheet resistance from 52.2k-Ω/sq to 18.0 Ω/sq. Although an increase in doping concentration of the conductive polymer reduced sheet resistance in low AgNW …

Resonant Spectra Of Metal Nanotoroids Of Various Sizes, Huong Quynh Tran

Electrical Engineering Undergraduate Honors Theses

Nowadays, the manipulation of light by using metallic nanostructures has wide applications in photonics, optoelectronics and energy conversion. Along with other universities all over the world, the University of Arkansas is researching on nano-antennas’ design, fabrication and applications. Current research in Dr. El-Shenawee’s Terahertz Imaging and Spectroscopy Computational Electromagnetics Group, has computationally investigated the behaviors of plasmonic nanostructures by using the commercial finite element electromagnetic solver Ansys® HFSS. This work reproduced the previous work of spectral absorption enhancement of infinite and finite arrays of silver and gold nanotoroids with sizes of the inner radii: 13nm – 21nm, while outer radius …

Large-Scale Graphene Film Deposition For Monolithic Device Fabrication, Khaled Al-Shurman

Graduate Theses and Dissertations

Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors.

The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an …

Generalized Ellipsometry Analysis Of Anisotropic Nanoporous Media: Polymer-Infiltrated Nanocolumnar And Inverse-Column Polymeric Films, Dan Liang

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Characterization of the structural and optical properties is a subject of significance for nanoporous material research. However, it remains a challenge to find non-destructive methods for investigating the anisotropy of porous thin films with three-dimensional nanostructures. In this thesis, a generalized ellipsometry (GE) analysis approach is employed to study two types of anisotropic nanoporous media: slanted columnar thin films (SCTFs) with polymer infiltration and inverse-SCTF polymeric films. The thesis presents the physical properties obtained from GE analysis, including porosity, columnar shape, principal optical constants, birefringence, etc.

The thesis reports on using a GE analysis approach, combining the homogeneous biaxial layer …

Porous Co3O4 Hollow Nanospheres Cathode Catalyst For High-Capacity And Long-Cycle Li-Air Batteries, Tong Liu, Na Li, Qing-Chao Liu, Xin-Bo Zhang

Journal of Electrochemistry

In this paper, a high specific surface area of porous Co3O4 hollow nanospheres was successfully synthesized via hydrothermal carbonization at 140 °C, followed by calcination using cobalt nitrate hexahydrate (Co(NO3)2·6H2O), hexamethylenetetramine (HMT), sucrose, and sodium citrate (Na3C6H5O7). The porous Co3O4 hollow nanospheres consisted of nanoparticles with high specific surface area of mesoporous structure, and could provide active reaction sites for OER and ORR. When used as lithium-air battery cathode catalyst, the Co3O4/Super P (SP) electrode exhibited excellent cycle performance, resulting in high capacity and long life of lithium-air batteries.

Electrospinning Of Polycaprolactone Core-Shell Nanofibers With Anti-Cancer Drug, Sakib Iqbal, Mujibur Khan, Saheem Absar, Andrew Diamanduros, Samuel Chambers

GS4 Student Scholars Symposium

Encapsulation of a model anti-cancer drug, 5-Fluorouracul (5-FU) into biocompatible core-shell nanofibers of polycaprolactone (PCL) nanofibers was fabricated using a coaxial electrospinning process. Our work aims to solve these issues using a novel method of fabrication of fibers featuring confinement of drugs within a biodegradable core-shell structure, thereby permitting sustained release of drugs to specific sites of treatment, such as tissues affected with tumor cells. The coaxial electrospinning was performed using a sheath polymer solution consisting of a 14 wt% PCL solution and a 5 wt% solution of 5-FU as the core solution. Dimethylformamide (DMF) was used as the solvent …

Investigations Of Carbon Nanotube Catalyst Morphology And Behavior With Transmission Electron Microscopy, Sammy M. Saber

Open Access Dissertations

Carbon nanotubes (CNTs) are materials with significant potential applications due to their desirable mechanical and electronic properties, which can both vary based on their structure. Electronic applications for CNTs are still few and not widely available, mainly due to the difficulty in the control of fabrication. Carbon nanotubes are grown in batches, but despite many years of research from their first discovery in 1991, there are still many unanswered questions regarding how to control the structure of CNTs. This work attempts to bridge some of the gap between question and answer by focusing on the catalyst particle used in common …

Growth Of Low Disorder Gaas/Algaas Heterostructures By Molecular Beam Epitaxy For The Study Of Correlated Electron Phases In Two Dimensions, John D. Watson

Open Access Dissertations

The unparalleled quality of GaAs/AlGaAs heterostructures grown by molecular beam epitaxy has enabled a wide range of experiments probing interaction effects in two-dimensional electron and hole gases. This dissertation presents work aimed at further understanding the key material-related issues currently limiting the quality of these 2D systems, particularly in relation to the fractional quantum Hall effect in the 2^nd Landau level and spin-based implementations of quantum computation.^ The manuscript begins with a theoretical introduction to the quantum Hall effect which outlines the experimental conditions necessary to study the physics of interest and motivates the use of the semiconductor growth …

Nanosized Fe2O3 On Three Dimensional Hierarchical Porous Graphene-Like Matrices As High-Performance Anode Material For Lithium Ion Batteries, Qin-Wei Zhang, Yun-Yong Li, Pei-Kang Shen

Journal of Electrochemistry

Ferric oxide (Fe₂O₃) as a promising anode material for lithium ion battery is due to its high theoretical capacity (1007 mAh·g^-1), earth abundance and low cost. The nanosized Fe₂O₃ on the three dimensional hierarchical porous graphene-like network (denoted as Fe₂O₃-3D HPG) has been synthesized by homogeneous precipitation and heat treatment. The 3D HPG can provide a highly conductive structure in conjunction to support well contacted Fe₂O₃ nanoparticles, and effectively enhance the mechanical strength of the matrices during volume changes, as well as improve the …

A Novel Nitrite Sensing Electrode Based On Au/Fe3O4/Chitosan Nanocomposite, Ying Dong, Yong Wang, Huan-Huan Xing, Jian-Ying Qu

Journal of Electrochemistry

A novel nitrite sensing electrode based on gold nanoparticles and iron oxides (Fe₃O₄) magnetic nanoparticles was fabricated with chitosan as the protective film on glassy carbon matrix. Experiment results showed that the sensing electrode exhibited good electrocatalytic activity toward oxidation of nitrite, and the oxidation peak current increased linearly with the concentration of nitrite varying from 5.0×10^-6 to 2.0×10^-3 mol·L^-1 (R=0.9996) with a detection limit of 7.1×10^-7 mol·L^-1 (S/N=3). The sensing electrode exhibited good sensitivity, selectivity and repeatability.

On Thermal Aging Prevention In Polymer Core Composite Conductor Rods, Joe D. Hoffman

Electronic Theses and Dissertations

Increased energy usage in the United States and worldwide is driving the demand for new technologies to transmit electrical power in greater quantities and with reliable, safe, and more efficient methods. One recent innovation is to replace the standard Aluminum Conductor Steel Reinforced electrical transmission conductor with a new conductor design that utilizes a fiber reinforced polymer core rod to support a fully annealed aluminum conductor. This new technology that includes a hybrid carbon fiber/epoxy and glass fiber/epoxy support core allows for better efficiency and for greater current to be transmitted in the same size and weight line. These new …

Biomimetic Oral Mucin From Polymer Micelle Networks, Sundar Prasanth Authimoolam

Theses and Dissertations--Chemical and Materials Engineering

Mucin networks are formed by the complexation of bottlebrush-like mucin glycoprotein with other small molecule glycoproteins. These glycoproteins create nanoscale strands that then arrange into a nanoporous mesh. These networks play an important role in ensuring surface hydration, lubricity and barrier protection. In order to understand the functional behavior in mucin networks, it is important to decouple their chemical and physical effects responsible for generating the fundamental property-function relationship. To achieve this goal, we propose to develop a synthetic biomimetic mucin using a layer-by-layer (LBL) deposition approach. In this work, a hierarchical 3-dimensional structures resembling natural mucin networks was generated …

Determination Of Current Density Distribution In An Electron Beam, Yudhishthir Prasad Kandel

Legacy Theses & Dissertations (2009 - 2024)

Electron beams are useful in many applications because they can be focused down to a spot far exceeding the physical limit of focusing visible light or x-rays. Additionally, electron beams are useful in transferring concentrated amounts of energy to a very small well defined region of a target for a fixed duration. This has led to the development of both scanning electron microscopes (SEMs) and electron beam lithography. The goal of this work was to develop a general method that accurately and easily yields the best estimate of the electron current density distribution of a focused electron beam, known as …

Implementation Of Strategies To Improve The Reliability Of Iii-Nitride Photodetectors Towards The Realization Of Visible And Solar-Blind Imaging Arrays, John Bulmer

Legacy Theses & Dissertations (2009 - 2024)

Ultraviolet (UV) radiation detectors are being heavily researched for applications in non-line-of-sight (NLOS) communication systems, flame monitoring, biological detection, and astronomical studies. These applications are currently being met by the use of Si-based photomultiplier tubes (PMTs), which are bulky, fragile, expensive and require the use of external filters to achieve true visible-blind and solar-blind operation.

Initiated Chemical Vapor Deposition (Icvd) Polymer Thin Films : Structure-Property Effects On Thermal Degradation And Adhesion, Vijay Jain Bharamaiah Jeevendrakumar

Legacy Theses & Dissertations (2009 - 2024)

Opportunities and challenges for chemical vapor deposition (CVD) of polymer thin films stems from their applications in electronics, sensors, and adhesives with demands for control over film composition, conformity and stability. Initiated chemical vapor deposition (iCVD) is a subset of the CVD technique that conjoins bulk free-radical polymerization chemistry with gas-phase processing. The novelty of iCVD technique stems from the use of an initiator that can be activated at low energies (150 – 300 °C) to react with surface adsorbed monomer to form a polymer film. This reduces risk for potential unwarranted side-reactions.

High Frequency Signal Transmission In Through Silicon Via Based 3d Integrated Circuit, Min Xu

Legacy Theses & Dissertations (2009 - 2024)

Through silicon vias (TSVs) enable 3-dimensional (3D) integrated circuits (ICs), which have the potential to reduce the power consumption, interconnect length and overall communication latency in modern nanoelectronics systems. High-speed signal transmission channels through stacked silicon substrates are critical for 3D heterogeneous integration. This work presents systematic analyses of fabricated 3D IC test structures. This includes test structure design, fabrication, experimental characterization, equivalent circuit modeling and full wave simulations for high-speed signal transmission of the TSV based 3D IC channels.

The Impact Of Seed Layer Structure On The Recrystallization Of Ecd Cu And Its Alloys, Brendan B. O'Brien

Legacy Theses & Dissertations (2009 - 2024)

Despite the significant improvements originally offered by the use of Cu over Al as the interconnect material for semiconductor devices, the continued down-scaling of interconnects has presented significant challenges for semiconductor engineers. As the metal line widths shrink, both the conductivity and reliability of lines decrease due to a stubbornly fine-grained microstructure in narrow lines.

Carbon 1d/2d Nanoelectronics : Integration And Device Applications, Zhaoying Hu

Legacy Theses & Dissertations (2009 - 2024)

Graphene is a one-atom thick planar monolayer of sp2-bonded carbon atoms organized in a hexagonal crystal lattice. A single walled carbon nanotube (CNT) can be thought of as a graphene sheet rolled up into a seamless hollow cylinder with extremely high length-to-diameter ratio. Their ultra-thin body, large surface area, and exceptional electronic, optical and mechanical properties make these low-dimensional carbon materials ideal candidates for electronic applications. However, adopting low-dimensional carbon materials into semiconductor industry faces significant material and integration challenges. There is an urgent need for research at fundamental and applicative levels to find a roadmap for carbon nanomaterial to …

Design And Development Of Stress Engineering Techniques For Iii-Nitride Epitaxy On Si, Jeff Leathersich

Legacy Theses & Dissertations (2009 - 2024)

III-Nitrides have been a heavily researched material system for decades. Their material properties are favorable for a number of applications, most commonly in the optoelectronic and power device industry. Currently a majority of commercialized devices are fabricated on sapphire and SiC substrates but these are expensive and limit the widespread commercialization of the technology. There is substantial ongoing research geared toward the development of GaN on Si substrates because of the significant cost saving that would be realized through the inexpensive, large wafer and maturity of Si fabrication. Significant challenges with the deposition of GaN on Si have, thus far, …

Systems Approach To Producing Electrospun Polyvinylidene Difluoride Fiber Webs With Controlled Fiber Structure And Functionality, Brian D. Bell

USF Tampa Graduate Theses and Dissertations

Polyvinylidene difluoride (PVDF) is a functional polymeric material that can be used for a wide variety of applications. There are many new future applications that were recently suggested for electrospun PVDF fibers. Electrospinning is a process capable of producing nano to micro sized PVDF fibers in a web. It is important to control the structure of the web during electrospinning because by controlling the structure of the web it is possible for the PVDF fiber web to have increased performance in comparison to other common forms of PVDF.

While past scientific literature focused on applications of PVDF fibers, little was …

Structures, Properties And Functionalities Of Magnetic Domain Walls In Thin Films, Nanowires And Atomic Chains: Micromagnetic And Ab Initio Studies, Liwei D. Geng

Dissertations, Master's Theses and Master's Reports - Open

Structures, properties and functionalities of magnetic domain walls in thin film, nanowires and atomic chains are studied by micromagnetic simulations and ab initio calculations in this dissertation. For magnetic domain walls in thin films, we computationally investigated the dynamics of one-dimensional domain wall line in ultrathin ferromagnetic film, and the exponent α = 1.24 ± 0.05 is obtained in the creep regime near depinning force, indicating the washboard potential model is supported by our simulations. Furthermore, the roughness, creep, depinning and flow of domain wall line with commonly existed substructures driven by magnetic field are also studied. Our simulation results …

Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab

Theses and Dissertations

Design and synthesis of porous organic polymers have attracted considerable attentions during the past decade due to their wide range of applications in gas storage, gas separation, energy conversion, and catalysis. Porous organic polymers can be pre-synthetically and post-synthetically functionalized with a wide variety of functionalities for desirable applications. Along these pursuits, we introduced new synthetic strategies for preparation of porous organic polymers for selective CO₂ capture.

Porous azo-linked polymers (ALPs) were synthesized by an oxidative reaction of amine-based monomers using copper(I) as a catalyst which leads to azo-linkage formation. ALPs exhibit high surface areas of up to 1200 …

Novel Engineered Nanomaterials For Water Remediation And Gas Adsorption: Graphene Oxide And Carbon Nanotubes Decorated With Metal-Organic Frameworks And Magnetic Nanoparticles, Vahid Jabbari

Open Access Theses & Dissertations

In the current study, a series of novel magnetic and non-magnetic hybrid nanocomposites based on metal-organic frameworks (MOFs) of M3(BTC)2 (M: Ni, Cu, Zn, and Cd), graphene oxide (GrO), and carbon nanotubes (CNTs), and Fe3O4 magnetic nanoparticles (MNPs) were developed via a green, simple and versatile solvothermal method at which GrO and CNT were used as platform to grow the MOFs and Fe3O4 MNPs over them. The as-synthesized nanocomposites were characterized by XRD, SEM, TEM, XPS, IR, Raman, TGA, and N2 adsorption/desorption isotherms. Morphological analysis confirmed successful growth of nano-size Fe3O4 MNPs and M3(BTC)2 MOFs over GrO and CNT platforms. …

Reconfigurable Solid-State Dye-Doped Polymer Ring Resonator Lasers, Hengky Chandrahalim, Xudong Fan

Faculty Publications

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3′-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G) and 3,3′-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm² per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm² per pulse …