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Theses and Dissertations--Chemistry

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Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle Jan 2020

Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle

Theses and Dissertations--Chemistry

This project was motivated by an in situ heating experiment in the transmission electron microscope (TEM) in which gold (Au) nanoparticles were observed to dissolve tin dioxide (SnO2) nanowires (NWs) under vacuum. The explanation for this observation was that the high-temperature and low-pressure environment of the TEM caused the reverse reaction of the well-known vapor-liquid-solid (VLS) method commonly used to grow NWs. In the VLS process, a metal catalyst absorbs reactant vapor until it becomes supersaturated. The precipitation of the NW occurs at the liquid-solid interface, which ceases when there is no longer reactant vapor, and the diameter of the …


Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance, Alex Boehm Jan 2020

Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance, Alex Boehm

Theses and Dissertations--Chemistry

Halide perovskites have generated tremendous interest as low-cost semiconductors for optoelectronics, such as photovoltaics, lasers, and light emitting diodes due to their extraordinary optical and transport properties. Perovskite photovoltaics in particular have demonstrated a meteoric rise in power conversion efficiencies and drawn considerable interest as a next-generation solar energy technology. The rapid development has centered around lead-based derivatives, and concerns regarding the toxicity of lead has sparked interest in low toxicity and more environmentally friendly perovskite derivatives. In this regime tin (Sn) is regarded as a prominent alternative owing to the ideal bandgap and reduced toxicity exhibited by Sn-halide perovskites. …


Applications Of Drones In Atmospheric Chemistry, Travis J. Schuyler Jan 2020

Applications Of Drones In Atmospheric Chemistry, Travis J. Schuyler

Theses and Dissertations--Chemistry

The emission of greenhouse gases (GHGs) has changed the composition of the atmosphere during the Anthropocene. A major technical and scientific challenge is quantifying the resulting fugitive trace gas fluxes under variable meteorological conditions. Accurately documenting the sources and magnitude of GHGs emission is an important undertaking for discriminating contributions of different processes to radiative forcing. Therefore, the adverse environmental and health effects of undetected gas leaks motivates new methods of detecting, characterizing, and quantifying plumes of fugitive trace gases. Currently, there is no mobile platform able to quantify trace gases at altitudes(UASs), or drones, can be deployed on-site in …


Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang Jan 2019

Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang

Theses and Dissertations--Chemistry

Lignin, the second most abundant biopolymer on earth, is potentially a replaceable source for bulky fuels and chemical feedstocks. There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages but relatively few reports of how those methods affect other linkages that are present in lignin. We investigated how the β-1 and β-5 linkages respond under oxidative conditions proposed for lignin deconstruction based on their effect on β-O-4 linkages. Mechanochemical treatment of lignin can greatly improve the yield of monomer products and we applied a mechanochemical approach, using powerful ring-and-puck milling to promote lignin degradation. Along with …


Surface And Structural Modification Of Carbon Electrodes For Electroanalysis And Electrochemical Conversion, Yan Zhang Jan 2018

Surface And Structural Modification Of Carbon Electrodes For Electroanalysis And Electrochemical Conversion, Yan Zhang

Theses and Dissertations--Chemistry

Electrocatalysis is key to both sensitive electrochemical sensing and efficient electrochemical energy conversion. Despite high catalytic activity, traditional metal catalysts have poor stability, low selectivity, and high cost. Metal-free, carbon-based materials are emerging as alternatives to metal-based catalysts because of their attractive features including natural abundance, environmental friendliness, high electrical conductivity, and large surface area. Altering surface functionalities and heteroatom doping are effective ways to promote catalytic performance of carbon-based catalysts. The first chapter of this dissertation focuses on developing electrode modification methods for electrochemical sensing of biomolecules. After electrochemical pretreatment, glassy carbon demonstrates impressive figures-of-merit in detecting small, redox-active …


Morphological And Energetic Effects On Charge Transport In Conjugated Polymers And Polymer-Nanowire Composites, Zhiming Liang Jan 2018

Morphological And Energetic Effects On Charge Transport In Conjugated Polymers And Polymer-Nanowire Composites, Zhiming Liang

Theses and Dissertations--Chemistry

Organic semiconductors have wide applications in organic-based light-emitting diodes, field-effect transistors, and thermoelectrics due to the easily modified electrical and optical properties, excellent mechanical flexibility, and solution processability. To fabricate high performance devices, it is important to understand charge transport mechanisms, which are mainly affected by material energetics and material morphology. Currently it is difficult to control the charge transport properties of new organic semiconductors and organic-inorganic nanocomposites due to our incomplete understanding of the large number of influential variables. Molecular doping of π-conjugated polymers and surface modification of nanowires are two means through which charge transport can be manipulated. …


Biomimetic Devices To Drive A Thermodynamically Uphill Reaction Using Light And To Degrade Industrial Waste Stream Components, Madison Joanne Sloan Jan 2017

Biomimetic Devices To Drive A Thermodynamically Uphill Reaction Using Light And To Degrade Industrial Waste Stream Components, Madison Joanne Sloan

Theses and Dissertations--Chemistry

Given the amount of industrial waste produced each year, as well as the accruing amount of greenhouse gases in our atmosphere produced by the burning of fossil fuels, it is imperative that humanity develop environmentally-sustainable sources of energy and methods of remediation. Nature achieves both of these by use of enzymes as catalysts, inspiring interest in designing biomimetic systems capable of harnessing clean energy and remediating industrial waste. This study examined the ability of enzymes in electrochemical and convective flow systems to achieve these tasks. The first portion studied the incorporation of enzymes into an electrochemical system to drive the …


Acenes, Heteroacenes And Analogous Molecules For Organic Photovoltaic And Field Effect Transistor Applications, Devin B. Granger Jan 2017

Acenes, Heteroacenes And Analogous Molecules For Organic Photovoltaic And Field Effect Transistor Applications, Devin B. Granger

Theses and Dissertations--Chemistry

Polycyclic aromatic hydrocarbons composed of benzenoid rings fused in a linear fashion comprise the class of compounds known as acenes. The structures containing three to six ring fusions are brightly colored and possess band gaps and charge transport efficiencies sufficient for semiconductor applications. These molecules have been investigated throughout the past several decades to assess their optoelectronic properties. The absorption, emission and charge transport properties of this series of molecules has been studied extensively to elucidate structure-property relationships. A wide variety of analogous molecules, incorporating heterocycles in place of benzenoid rings, demonstrate similar properties to the parent compounds and have …


Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu Jan 2017

Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu

Theses and Dissertations--Chemistry

Metal oxides are of interest not only because of their huge abundance but also for their many applications such as for electrocatalysts, gas sensors, diodes, solar cells and lithium ion batteries (LIBs). Nano-sized metal oxides are especially desirable since they have larger surface-to-volume ratios advantageous for catalytic properties, and can display size and shape confinement properties such as magnetism. Thus, it is very important to explore the synthetic methods for these materials. It is essential, therefore, to understand the reaction mechanisms to create these materials, both on the nanoscale, and in real-time, to have design control of materials with desired …


Addressing Public Health Risks Of Persistent Pollutants Through Nutritional Modulation And Biomimetic Nanocomposite Remediation Platforms, Bradley J. Newsome Jan 2014

Addressing Public Health Risks Of Persistent Pollutants Through Nutritional Modulation And Biomimetic Nanocomposite Remediation Platforms, Bradley J. Newsome

Theses and Dissertations--Chemistry

Due to their relative chemical stability and ubiquity in the environment, chlorinated organic contaminants such as polychlorinated biphenyls (PCBs) pose significant health risks and enduring remediation challenges. Engineered nanoparticles (NPs) provide a novel platform for sensing/remediation of these toxicants, in addition to the growing use of NPs in many industrial and biomedical applications, but there remains concern for their potential long-term health effects. Research highlighted herein also represents a transdisciplinary approach to address human health challenges associated with exposure to PCBs and NPs. The objectives of this dissertation research are two-fold, 1) to develop effective methods for capture/sensing and remediation …


Bifunctional Bisphosphonates For Delivering Biomolecules To Bone, Jivan N. Yewle Jan 2012

Bifunctional Bisphosphonates For Delivering Biomolecules To Bone, Jivan N. Yewle

Theses and Dissertations--Chemistry

Active targeting with controlled delivery of therapeutic agents to bone is an ideal approach for treatment of several bone diseases. Since bisphosphonates (BPs) are known to have high affinity to bone mineral and are being widely used in treatment of osteoporosis, they are well-suited for drug targeting to bone. For this purpose, bifunctional hydrazine-bisphosphonates (HBPs) with spacers of various lengths and lipophilicity were synthesized and studied. Crystal growth inhibition assays demonstrated that the HBPs with shorter spacers bound more strongly to bone mineral, hydroxyapatite (HA), than did alendronate. HBPs were also demonstrated to be non-toxic to MC3T3-E1 pre-osteoblasts. The targeted …


Investigations Of Oxidative Stress Effects And Their Mechanisms In Rat Brain After Systemic Administration Of Ceria Engineered Nanomaterials, Sarita S. Hardas Jan 2012

Investigations Of Oxidative Stress Effects And Their Mechanisms In Rat Brain After Systemic Administration Of Ceria Engineered Nanomaterials, Sarita S. Hardas

Theses and Dissertations--Chemistry

Advancing applications of engineered nanomaterials (ENM) in various fields create the opportunity for intended (e.g. drug and gene delivery) or unintended (e.g. occupational and environmental) exposure to ENM. However, the knowledge of ENM-toxicity is lagging behind their application development. Understanding the ENM hazard can help us to avoid potential human health problems associated with ENM applications as well as to increase their public acceptance. Ceria (cerium [Ce] oxide) ENM have many current and potential commercial applications. Beyond the traditional use of ceria as an abrasive, the scope of ceria ENM applications now extends into fuel cell manufacturing, diesel fuel additives …