Physical Sciences and Mathematics Commons^™

A Study On The Oxidation Of Hydrogen Peroxide At Au(111) And Au(100) Electrodes, Yong-Li Zheng, Jie Wei, Yan-Xia Chen

Journal of Electrochemistry

The oxidation reactions of hydrogen peroxide (H₂O₂) at Au(111) and Au(100) electrodes in 0.1 mol·L^-1 HClO₄ were investigated by using rotating disk electrode system. It was found that H₂O₂ could be readily oxidized to O₂ at both Au(100) and Au(111) surfaces with the onset potential close to its equilibrium potential. In contrast, the onset overpotential for H₂O₂ reduction was above 0.4 V, while the onset overpotential for H₂O₂ oxidation at Au(100) was ca. 0.1 V more negative than that at Au(111), this is probably …

Synthesis Of Ultrathin Co3O4 Nanoflakes Film Material For Electrochemical Sensing, Hui-Juan Wang

Journal of Electrochemistry

Ultrathin cobalt oxide (Co₃O₄ ) nanoflakes film material was synthesized by using an electro-deposited cobalt layer as a raw material through a simple oxidation method and followed by a heat treatment at 350 ^oC. The physical characterizations of the Co₃O₄ nanoflakes film were performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) technologies, and the electrochemical activity was measured by cyclic voltammetry (CV). As a promising material for electrochemical sensing, the as-synthesized ultrathin Co₃O₄ nanoflakes film material exhibited excellent electrochemical activity for H₂O …

Stm Investigation Of Oxygen Reduction Reaction On Solid Interface In Fuel Cell, Zhen-Feng Cai, Bing Sun, Wen-Jie Jiang, Ting Chen, Dong Wang, Li-Jun Wan

Journal of Electrochemistry

An electrocatalyst for oxygen reduction reaction (ORR) is an important component for fuel cells. An investigation at interfacial electrochemical reactions toward ORR at a molecular scale benefits mechanistic understanding as well as rational design of catalysts. Scanning tunneling microscopy (STM) has been proven to be a powerful tool to monitor chemical reactions and to provide in-situ information about the interfacial electrochemical reactions at a molecular level. This review summarizes the recent STM studies in monitoring the interface processes such as morphological changes, molecular changes, reaction intermediates, and oxidation products. The prospects of future development in this field are outlined.

Syntheses Of Ag@Pd@Pt Nanoparticles With Tunable Shell Thickness For Electrochemical Oxidation Of Formic Acid, Xiao-Dong Lin, Du-Hong Chen, Zhong-Qun Tian

Journal of Electrochemistry

In an effort to lower cost of a catalyst, the silver (Ag) core with palladium (Pd) layer then platinum (Pt) island (Ag@Pd@Pt) nanoparticles were synthesized and the electrocatalytic activity of Ag@Pd@Pt nanoparticles on formic acid was compared with that of Au@Pd@Pt nanoparticles reported previously. The results showed that the existence of a small amount of Pt could significantly improve the activity of the catalyst. When the surface coverage of Pt approached 0.5 monolayers, the activity of Ag@Pd@Pt nanoparticles reached the maximum. Though the onset potential of the electro-oxidation was slightly more positive (about 50 mV), the overall electrocatalytic activity of …

Chitosan/Nonahydrate Gel Derived Fe-N-Doped Porous Carbon Sheet As High-Efficient Orr Electrocatalyst, Fan-Lu Meng, Xin-Bo Zhang, Jun-Min Yan

Journal of Electrochemistry

The chitosan/nonahydrate gel was used as a precursor to realize the uniform mixture of N-polymer and metal salt. After lyophilization treatment, the gel went through heat treatment and acid etch. Accordingly, the Fe-N-doped porous carbon sheet with homogenous composition and microstructure was prepared. Compared with the commercial Pt/C catalyst, the Fe-N-doped porous carbon sheet exhibited more positive onset potential and half-wave potential, higher current density, and especially, excellent durability. The power density of 318 mW·cm^-2 was obtained in alkaline fuel cell with the Fe-N-doped porous carbon sheet as a cathode catalyst, which is higher than 267 mW·cm^-2 with …

Large Scale Brownian Dynamics Simulation Of Dilute And Semidilute Polymeric Solutions, Amir Saadat

Doctoral Dissertations

Excluded Volume (EV) and Hydrodynamic Interactions (HI) play a central role in static and dynamic properties of macromolecules in solution under equilibrium and nonequilibrium settings. The computational cost of incorporating HI in mesoscale Brownian dynamics (BD) simulations, particularly in the semidilute regime has motivated significant research aimed at development of high-fidelity and efficient techniques.

In this study, I have developed several algorithms for the mesoscale bead-spring representation of a macromolecular solution in dilute and semidilute regimes. The Krylov subspace method enables fast calculation of single chain dynamics with simulation time scaling of O(N_b²) [order N …

Preliminary Investigation For The Development Of Surrogate Debris From Nuclear Detonations In Marine-Urban Environments, Adam G. Seybert

Masters Theses

No nuclear weapon has ever been detonated in a United States city. However, this also means the nuclear forensic community has no actual debris from which to develop analytical methods for source attribution, making the development of surrogate nuclear debris a vital undertaking. Moreover, the development of marine-urban debris presents an unusual challenge because unlike soil and urban structures, which remain compositionally consistent, the elemental composition of harbor and port waters fluctuates considerably due to natural phenomenon and human activity. Additionally, marine vessel composition and cargo can vary dramatically. While early US nuclear tests were carried out in shallow-water coastal …

Design And Synthesis Of Dynamic Covalent Polymer Scaffolds With Controlled Architectures, Emily Annette Hoff

Dissertations

The design and synthesis of functional, controlled polymer architectures is essential to the development of new materials with precise and tailorable properties or applications. The work described in this dissertation focuses on the development of controlled polymer architectures with dynamic linkages for the design of multifunctional materials and surfaces via robust, efficient, and stimuli-responsive strategies.

In Chapter III, a post-polymerization modification strategy based on ambient temperature nucleophilic chemical deblocking of polymer scaffolds bearing N-heterocycle blocked isocyanate moieties is reported. Room temperature RAFT polymerization of three azole-N-carboxamide methacrylates, including 3,5-dimethyl pyrazole, imidazole, and 1,2,4-triazole derivatives, afforded reactive polymer scaffolds …

Plasma Processes And Polymers Third Special Issue On Plasma And Cancer, Mounir Laroussi, Annemie Bogaerts, Nazir Barekzi

Electrical & Computer Engineering Faculty Publications

(First paragraph) This issue of Plasma Processes and Polymers is the third in a series on the applications of low temperature plasma (LTP) against cancer, or “plasma oncology.” The papers in this issue are inspired from the talks given at the third International Workshop on Plasma for Cancer Treatment (IWPCT) which took place on April 11–12, 2016 in Washington, DC, USA. IWPCT is an international workshop that was created in 2014 as a venue to share cutting edge plasma oncology research. The first IWPCT was held in Washington DC, under the co-chairmanship of Prof. Mounir Laroussi (Old Dominion University) and …

Conformationally Superarmed S-Ethyl Glycosyl Donors As Effective Building Blocks For Chemoselective Oligosaccharide Synthesis In One Pot, Mithila Bandara, Jagodige Yasomanee, Nigam Rath, Christian Pedersen, Mikael Bols, Alexei Demchenko

Chemistry & Biochemistry Faculty Works

A new series of superarmed glycosyl donors has been investigated. It was demonstrated that the S-ethyl leaving group allows for high reactivity, which is much higher than that of equally equipped S-phenyl glycosyl donors that were previously investigated by our groups. The superarmed S-ethyl glycosyl donors equipped with a 2-O-benzoyl group gave complete β-stereoselectivity. Utility of the new glycosyl donors has been demonstrated in a one-pot one-addition oligosaccharide synthesis with all of the reaction components present from the beginning.

Photocatalytic Reduction Of Co2 With Tunable Bandgap And Bandedge Materials, Thuhuong T. Ngo

USF Tampa Graduate Theses and Dissertations

Solar energy is a sustainable resource which has substantial potential to meet the increasing demand for renewable energy. Though there has been some success in harvesting solar energy for electricity production, converting solar energy to chemical energy as fuels is still a challenge due to low efficiency.

Since the discovery of TiO₂ photocatalysts for splitting water (4) and reducing CO₂ (5) to form useful chemical feedstock such as H₂, CO and CH₄, much research has been done to increase the efficiency of photocatalysts. However, the current conversion efficiency of photocatalysts remains low (~5%) (6, …

Peridynamic Modeling Of Ruptures In Biomembranes, Michael Taylor, Irep Gözen, Samir Patel, Aldo Jesorka, Katia Bertoldi

Michael Taylor

We simulate the formation of spontaneous ruptures in supported phospholipid double bilayer membranes, using peridynamic modeling. Experiments performed on spreading double bilayers typically show two distinct kinds of ruptures, floral and fractal, which form spontaneously in the distal (upper) bilayer at late stages of double bilayer formation on high energy substrates. It is, however, currently unresolved which factors govern the occurrence of either rupture type. Variations in the distance between the two bilayers, and the occurrence of interconnections (“pinning sites”) are suspected of contributing to the process. Our new simulations indicate that the pinned regions which form, presumably due to …

Kinetics And Dynamics Of Electrophoretic Translocation Of Polyelectrolytes Through Nanopores, Harshwardhan Katkar

Doctoral Dissertations

The idea of sequencing a DNA based on single-file translocation of the DNA through nanopores under the action of an electric field has received much attention over the past two decades due to the societal need for low cost and high-throughput sequencing. However, due to the high speed of translocation, interrogating individual bases with an acceptable signal to noise ratio as they traverse the pore has been a major problem. Experimental facts on this phenomenon are rich and the associated phenomenology is yet to be fully understood. This thesis focuses on understanding the underlying principles of polymer translocation, with an …

Polymer And Small Molecule Designs For Anion Conducting Membranes: Connected Ion-Channel Morphologies And Highly Alkaline Stable Ammonium Cations, Sedef P. Ertem

Doctoral Dissertations

Fuel cells are one of the oldest sustainable energy generation devices, converting chemical energy into electrical energy via reverse-electrolysis reactions. With the rapid development of polymer science, solid polymer electrolyte (SPE) membranes replaced the conventional liquid ion transport media, rendering low-temperature fuel cells more accessible for applications in portable electronics and transportation. However, SPE fuel cells are still far from commercialization due to high operation cost, and insufficient lifetime and performance limitations. Anion exchange membrane fuel cells (AEMFCs) are inexpensive alternatives to current proton exchange membrane fuel cell (PEMFC) technology, which relies on utilizing expensive noble-metal catalysts and perfluorinated SPE …

Peridynamic Modeling Of Ruptures In Biomembranes, Michael Taylor, Irep Gözen, Samir Patel, Aldo Jesorka, Katia Bertoldi

Mechanical Engineering

We simulate the formation of spontaneous ruptures in supported phospholipid double bilayer membranes, using peridynamic modeling. Experiments performed on spreading double bilayers typically show two distinct kinds of ruptures, floral and fractal, which form spontaneously in the distal (upper) bilayer at late stages of double bilayer formation on high energy substrates. It is, however, currently unresolved which factors govern the occurrence of either rupture type. Variations in the distance between the two bilayers, and the occurrence of interconnections (“pinning sites”) are suspected of contributing to the process. Our new simulations indicate that the pinned regions which form, presumably due to …

The Study Of Dynamical Electrochemical Impedance Spectroscopy For Oxygen Reduction Reaction On Pt/C Catalyst, Kun-Ming Shi, Jian-Wei Guo, Jia Wang

Journal of Electrochemistry

With joint techniques of rotating disc electrode(RDE) and electrochemical impedance spectroscopy(EIS), and further establishment on equivalent circuit model, this paper studied oxygen reduction reaction(ORR) on commercial Pt/C catalyst in acid medium. Our results found that the dynamical interface on Pt/C consists of two independent processes: 1) the PtO reduction from Pt surface, 2) the new PtO formation from ORR, thus providing key clues for catalyst stability and activity. This also implied that the dynamical interface facilitates reconstruction for porous electrode, and matches with mass transfer. One important issue is discovered that at high overpotential, the high reaction rate for ORR …

Template-Assisted Hydrothermal Synthesis Of Nio@Co3O4 Hollow Spheres With Hierarchical Porous Surfaces For Supercapacitor Applications, Wen Zhou, Xue-Feng Lu, Ming-Mei Wu, Gao-Ren Li

Journal of Electrochemistry

Hollow structures have shown great potentials in a variety of important applications, such as energy conversion and storage. In order to further enhance the performance, the rational design of hollow structures with higher complexity in terms of composition and structure is highly desirable and still remains a great challenge. In this work, an efficient strategy was established for the fabrication of novel NiO@Co₃O₄ hollow spheres (HSs) with hierarchical porous surfaces by silica spheres template-assisted hydrothermal synthesis. The as-fabricated NiO@Co₃O₄ HSs showed high specific surface area of 219.68 m²·g^-1, and significant …

Continuous Synthesis And Condition Exploration Of Precursor Ni1/3co1/3mn1/3(Oh)2 Ternary Cathode Material, Jiang Zhi-Jun, Ya-Li Zhang, Wang Qian, Zhang Hui

Journal of Electrochemistry

Commercial LiNi_1/3Co_1/3Mn_1/3(OH)₂ ternary material is generally prepared by a combination of co-precipitation and solid state reaction method. The particle size distribution and morphology of Ni_1/3Co_1/3Mn_1/3(OH)₂ precursor have a great impact on the electrochemical performance of LiNi_1/3Co_1/3Mn_1/3O₂. In this work, the precursor Ni_1/3Co_1/3Mn_1/3(OH)₂ ternary cathode material was prepared by co-precipitation method with MnSO₄, NiSO₄, and CoSO₄ as raw materials, NaOH as a precipitating agent and NH_{3 …}

Numerical Simulation Of Residual Stress In Low-Temperature Colossal Carburized Layer On Austenitic Stainless Steel, Dongsong Rong, Yong Jiang, Jianming Gong, Yawei Peng

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Recent Approaches In Designing Bioadhesive Materials Inspired By Mussel Adhesive Protein, Pegah Kord Forooshani, Bruce P. Lee

Department of Biomedical Engineering Publications

Marine mussels secret protein-based adhesives, which enable them to anchor to various surfaces in a saline, intertidal zone. Mussel foot proteins (Mfps) contain a large abundance of a unique, catecholic amino acid, Dopa, in their protein sequences. Catechol offers robust and durable adhe-sion to various substrate surfaces and contributes to the curing of the adhesive plaques. In this article, we review the unique features and the key functionalities of Mfps, catechol chemistry, and strategies for preparing catechol-functionalized poly- mers. Specifically, we reviewed recent findings on the contributions of various features of Mfps on interfacial binding, which include coacervate formation, surface …

Effect Of Surface Treatment On Liquid Adhesion Inside 3-D Structures, Madani A. Khan, Jeffrey Alston, Andrew Guenthner, Jacob Zavala

STAR Program Research Presentations

This study explores the relationship between chemical surface treatments on the interior of glass tubes and their resistance to fluid flow. By treating the interior of the tubes with functional silanes we can decrease or increase the interaction of the tube walls with the fluid column, which translates to changes in fluid column height for a given pressure differential. Resistance to fluid flow is quantified by using the tubes as integral parts of a barometric pressure column and measuring the changes in column height as the fluid is pulled into the tube by a set pressure differential. The barometric pressure …

Modeling Pyrolysis Of Large Coal Particles With Many Species, Jianqing Li

Master's Theses (2009 -)

Coal currently supplies 40% of the world’s electricity needs, and is one of the most important energy sources. As the initial stage of coal combustion, pyrolysis is a thermal decomposition process which converts coal into light gases and tars, which are subsequently consumed in combustion reactions, as well as solid char. Recently there has been interest in using slow pyrolysis as a stand-alone process for the production of chemicals and fuels from large (mm-scale) coal particles. Simulations can be used to efficiently study the impact of pyrolysis conditions on gas, tar and char yields, as well as gas and tar …

An Unexpected Restructuring Of Combustion Soot Aggregates By Subnanometer Coatings Of Polycyclic Aromatic Hydrocarbons, Chao Chen, Xiaolong Fan, Tasneem Shaltout, Chong Qiu, Yan Ma, Andrew Goldman, Alexei F. Khalizov

Chemistry and Chemical Engineering Faculty Publications

We investigated the effect of thin polycyclic aromatic hydrocarbon (PAH) coatings on the structure of soot aggregates. Soot aerosol from an inverted diffusion burner was size classified, thermally denuded, coated with six different PAHs, and then characterized using scanning electron microscopy, light scattering, and mass-mobility measurements. Contrary to our expectation, significant restructuring was observed in the presence of subnanometer layers of pyrene, fluoranthene, and phenanthrene. These PAHs remained in subcooled liquid state in thin films, whereby the liquid layer acted as a lubricant, reducing the force required to initiate the restructuring. Thin layers of PAH of higher melting temperatures (perylene, …

Development Of Ultrasonic Techniques For Characterization Of Liquid Mixtures, William A. Cooke

Electronic Thesis and Dissertation Repository

To evaluate the suitability of ultrasonic techniques for on-line process monitoring applications, an ultrasonic probe was used to measure acoustic velocity, acoustic impedance, and isentropic compressibility of hydrocarbons (including n-, iso-, and cycloalkanes, toluene, mineral oil, and crude oil) and polar liquids (alcohols, water, salt water) over a temperature range of 25-60°C. Temperature, carbon chain length, molecular shape, and intermolecular forces had significant effects on ultrasonic parameters. Relationships between media characteristics and observed ultrasonic parameters were modeled using empirical-least squares equations. The same parameters were measured in binary mixtures of hydrocarbons in heptane, as well as polar liquids in ethanol. …

Grain Boundary Induced Bias Instability In Soluble Acene-Based Thin-Film Transistors, Ky V. Nguyen, Marcia M. Payne, John E. Anthony, Jung Hun Lee, Eunjoo Song, Boseok Kang, Kilwon Cho, Wi Hyoung Lee

Chemistry Faculty Publications

Since the grain boundaries (GBs) within the semiconductor layer of organic field-effect transistors (OFETs) have a strong influence on device performance, a substantial number of studies have been devoted to controlling the crystallization characteristics of organic semiconductors. We studied the intrinsic effects of GBs within 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) thin films on the electrical properties of OFETs. The GB density was easily changed by controlling nulceation event in TES-ADT thin films. When the mixing time was increased, the number of aggregates in as-spun TES-ADT thin films were increased and subsequent exposure of the films to 1,2-dichloroethane vapor led to a significant …

Capture And Recycle Of Industrial Co2 Emissions Using Mircoalgae, Michael H. Wilson, Daniel T. Mohler, John G. Groppo, Thomas E. Grubbs, Stephanie Kesner, E. Molly Frazar, Aubrey Shea, Czarena L. Crofcheck, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

A novel cyclic flow photobioreactor (PBR) for the capture and recycle of CO₂ using microalgae was designed and deployed at a coal-fired power plant (Duke Energy’s East Bend Station). The PBR was operated continuously during the period May–September 2015, during which algae productivity of typically 0.1–0.2 g/(L day) was obtained. Maximum CO₂ capture efficiency was achieved during peak sunlight hours, the largest recorded CO₂ emission reduction corresponding to a value of 81 % (using a sparge time of 5 s/min). On average, CO₂ capture efficiency during daylight hours was 44 %. The PBR at East Bend …

Hydrothermal One-Step Synthesis Of Layered Nickel/Cobalt Double Hydroxide With Using Shape-Directing Agent And Homogeneous Precipitating Agent, Li-Wei Zhu, Yun-Hai Yan, Hui Jia, Run-Fen Liang

Journal of Electrochemistry

Nickel/cobalt double hydroxide (Ni/Co-DH) has been prepared by facile hydrothermal one-step synthesis method using hexamethylene tetramine (HMT) as a homogeneous precipitating agent and cetyltrimethylammonium bromide (CTAB) as a shape-directing agent. With the hydrolysis of HMT and the use of CTAB, the Ni/Co-DH could be synthesized without additional alkali source, and in the meantime, the Ni/Co-DH exhibited a controlled mesopore size of 13.4 nm and a large BET surface area of 93.6 m² •g^-1 . The X-ray diffraction (XRD) pattern displays that the Ni/Co-DH existed as a mixture of α-Ni(OH)₂-β-Co(OH)₂. The scanning electron microscope (SEM) …

Nanostructured Thin Film Synthesis By Aerosol Chemical Vapor Deposition For Energy Storage Applications, Tandeep Singh Chadha

McKelvey School of Engineering Theses & Dissertations

Renewable energy sources offer a viable solution to the growing energy demand while mitigating concerns for greenhouse gas emissions and climate change. This has led to a tremendous momentum towards solar and wind-based energy harvesting technologies driving efficiencies higher and costs lower. However, the intermittent nature of these energy sources necessitates energy storage technologies, which remain the Achilles heel in meeting the renewable energy goals. This dissertation focusses on two approaches for addressing the needs of energy storage: first, targeting direct solar to fuel conversion via photoelectrochemical water-splitting and second, improving the performance of current rechargeable batteries by developing new …

Mechanism Of Ethanol Partial Oxidation Over Titania Supported Vanadia Catalysts: Geometric And Electronic Structure Consequences On Reaction Kinetics, Dongmin Yun

Electronic Thesis and Dissertation Repository

Supported vanadium oxide catalysts (VO_x) are used for a wide range of industrial processes. A significant amount of research has been carried on this specific system with the aim to identify the critical parameters involved in catalytic activity. The results on this relative large body of research indicate that the catalyst support plays a critical role in determining the catalytic activity of vanadia and the use of titanium dioxide as support renders a catalyst with superior activity. Studies on supported vanadia on titanium oxide (VO_x/TiO₂) have provided an understanding on support interactions that result …

Adsorption Kinetics Of Bovine Serum Albumin To Strong Anion Exchange Adsorbents: Application Of The Pore Diffusion Model To Resins And Membranes, Sarah Catherine Jensen

Graduate Theses - Chemical Engineering

The replacement of traditional bead-based chromatography by membranes has gained recent interest in the bioseparations industry. However, membranes have drawbacks such as lower binding capacity that make them unrealistic for some applications. The goal of this work is to compare the adsorption kinetics of anion exchange bead-based resin and membranes both on a theoretical modeling level and experimental level. Bovine serum albumin (BSA) was adsorbed to Q Sepharose FastFlow resin and Sartobind Q membrane to obtain adsorption equilibrium characteristics and kinetic data. A numerical solution was used to fit the pore diffusion model to the data and estimate a pore …