Inorganic Chemistry Commons^™

Carbon Dioxide Reduction On Large Area Liquid Metal Gallium-Indium Electrocatalysts, Thomas Hollis

Chemistry & Biochemistry Undergraduate Honors Theses

Carbon dioxide (CO₂) is widely known as a greenhouse gas that contributes to global warming due to the burning of fossil fuels. The carbon dioxide reduction reaction (CO₂RR) is widely studied to reutilize CO₂ to useful products, including methane, ethane, and carbon monoxide. This project studies the use of liquid metal gallium-indium as an electrocatalyst to perform CO₂ reduction to carbon monoxide (CO) or possibly solid carbon in various solutions. Gallium-indium is characterized and studied through its “wetting” properties and adhesion to substrate foil through the measurement of contact angles inside solution. These liquid …

Catalytic Activity Of Tungsten-Dioxo And Tungsten-Diimido Complexes, Kayla Denike

Graduate Theses and Dissertations

Due to the significant decline in the availability of petrochemical resources and the increasing demand for the useful olefin mixtures extracted from oil, a sustainable and efficient alternative to these materials has become vital. Fortunately, renewable biomass derived materials may serve as a sustainable solution to the limited resources problem. Molecules derived from the degradation of biomasses are highly oxygenated and highly functionalized. Developing processes to efficiently defunctionalize these oxygen-rich materials will lead to potential up-conversion to carbon chemicals. Homogeneous catalytic deoxygenation processes present an opportunity to access valuable carbon commodity chemicals from biomass derived polyols. This dissertation details the …

Hierarchically Structured Photoelectrodes Via Atomic Layer Deposition, Justin Rowan Reed Demoulpied

Graduate Theses and Dissertations

In the search for a sustainable method to meet increasing energy needs, solar energy emerges as an underutilized, plentiful resource. Solar intermittency and requirements for transportation necessitate storing solar energy in the form of chemical bonds via artificial photosynthesis. Photoelectrochemical (PEC) water splitting generates hydrogen fuel from solar energy and water. A semiconducting material that successfully meets the complex requirements for building an industrially scalable PEC device has yet to emerge. This is leading to a reevaluation of materials previously overlooked within PEC research, mainly materials with limitations such as minimal charge carrier mobility and propensity to corrosion under illumination …

Colloidal Monolayers For Concentration Light In Ultra-Thin Semiconductor Layers, Rachel Cherry

Graduate Theses and Dissertations

Thin film semiconductors are used as photoconductive absorber layers for the development of broadband terahertz generation. Using a femtosecond laser pulse, the generation of a transient increase in the conductivity occurs by photoexciting conduction band electrons in the semiconductor. These thermalize through the emission of terahertz radiation. The route to terahertz generation is not particularly efficient as significant losses come from the absorption in the substrate that is beneath the photoconductive antenna layer. This work explores the application of hexagonally close-packed monolayers of chemically synthesized nanospheres as a potential light concentration method for ultra-thin films of GaAs and black phosphorus …

Understanding Interfacial Reactions Initiating On Electrode Materials For Energy Storage Technologies, Jingnan Li

Graduate Theses and Dissertations

Since the first generation of lithium-ion batteries featured lithium cobalt oxide cathode and carbon anode commercialized in the 1990s, the high-capacity materials with lower cost are in demand to further increase the battery energy density. Lithium metal and silicon anode are promising high-capacity anode materials to achieve next-generation lithium batteries. However, both the materials actively react in electrolytes and suffer from dramatic volume change. Therefore, a reliable passivation layer at the electrolyte/electrode interphase (i.e., solid electrolyte interphase, or “SEI”) is required to support the long-term cycling of both materials. Cetrimonium hydro fluoride (CTAHF2) has been proposed and synthesized as an …

Understanding The Interfacial Reactions Initiating On Lithium Metal Surfaces In Next-Generation Battery Technologies, Joshua A. Lochala

Graduate Theses and Dissertations

Li-ion batteries have started to reach the theoretical maximum energy. Next-generation batteries represent the future of portable energy sources for vehicle electrification and grid energy storage. Li metal battery is one of the most promising next-generation battery technologies that could potentially double the cell-level energy of conventional Li-ion batteries. However, Li metal has multiple drawbacks that require addressing before realization. These drawbacks include dendrite formation leading to internal short and increasing internal resistance due to the breakdown of electrolyte, leading to rapid cell death. These problems stem from the interfacial reactions occurring during the plating and stripping of Li metal. …

Ensemble And Single Particle Studies Of Cation Exchange In Cuins2/Zns Qds And Their Application In Super-Resolution Imaging, Anh Tue Nguyen

Graduate Theses and Dissertations

Colloidal quantum dots (QDs) have great potential in many applications such as bioimaging, light emitting diodes, solar cells and lasers. However, a great number of studies have been focused on Cd based (II-VI) and Pb (IV-VI) based materials which are not suitable for mass production. Therefore, alternative types of QD containing less toxic materials have been introduced, including CuInS2 QDs. This I-III-VI semiconductor nanocrystals also attract lots of attention due to their large Stock shift, long fluorescence lifetime and high defect tolerance, making them attractive emitters for applications in bioimaging, photovoltaics and light emitting diodes.

In the first project, we …

Surface Immobilization Of Terpyridine Compounds, Elizabeth Hallett

Chemical Engineering Undergraduate Honors Theses

The deoxydehydration (DODH) of polyols to alkenes is a promising method of producing high-value chemical feedstocks from biomass-derived materials. Current catalytic systems for DODH require the use of costly reducing agents that generate stoichiometric amounts of chemical waste. Immobilizing catalysts on electrode surfaces using chemical linking groups eliminates the need for sacrificial reductants. In this work, glassy carbon electrodes were modified with 4’-(3,4-dihydroxyphenyl)-2,2’:6’,2’’-terpyridine to investigate o-benzoquinone as a potential linking group for DODH, and possibly for other reactions. Previous studies involving electrodes modified with quinone-containing compounds have primarily been focused on catalyzing the oxidation of NADH; the nature or …

An Electrochemical Characterization Of A Vanadium-Based Deoxydehydration Catalyst, Joel Eric Baker

Graduate Theses and Dissertations

Alternative methods for the conversion of polyols into olefins, be it for carbon storage or hydrocarbon fuel production, have become prevalent in today’s chemical industry. One process in particular, deoxydehydration (DODH) has been proven effective in taking sustainable biomass derivatives and converting them through the utilization of various homogenous metal catalysts. While this process may show productive yields and material conversion, it is hindered by the need of a sacrificial reductant. This makes a novel process economically unviable and relatively unused outside of scientific research. That fact begs the question: Can the process be improved? It is proposed here that …

Controlled Synthesis And Utilization Of Metal And Oxide Hybrid Nanoparticles, Cameron Cowgur Crane

Graduate Theses and Dissertations

This dissertation reports the development of synthetic methods concerning rationally-designed, hybrid, and multifunctional nanomaterials. These methods are based on a wet chemical, solution phase approach that utilizes the knowledge of synthetic organic and inorganic chemistry to generate building blocks in solution for the growth of nanocrystals and hybrid nanostructures. This work builds on the prior knowledge of shape-controlled synthesis of noble metal nanocrystals and expands into the challenging realm of the more reactive first row transition metals. Specifically, a microemulsion sol-gel method was developed to synthesize Au-SiO2 dimers as precursors for the synthesis of segmented heterostructures of noble metals that …

Bond Length And Bond Valence For Tungsten-Oxygen And Tungsten-Sulfur Bonds, F. D. Hardcastle, R. Lykins

Journal of the Arkansas Academy of Science

In 1947, Linus Pauling presented an “empirical” dependence of bond valence (s, also referred to as bond order) and bond length R: s = exp[(R₀-R)/b], where R₀ is bond length of unit valence and “b” is a fitting parameter. Recently, an expression was derived for relating the b fitting parameter to theoretically derived atomic orbital exponents. With a method to calculate b, both R₀ and atomic orbital exponents can be experimentally determined through optimized fitting for W-O and W-S bonds. In the present study, bond …

Bond Length And Bond Valence Relationships For Chromium Oxides, Chromium Sulfides, Molybdenum Oxides, And Molybdenum Sulfides, J. Labrecque, F. D. Hardcastle

Journal of the Arkansas Academy of Science

Pauling determined an empirical logarithmic dependence of bond order (bond valence), s, to bond length, R, s = exp(R₀ – R/ b), where R₀ is unit bond length and b is a fitting parameter. Recently, an expression was derived for relating the b fitting parameter to theoretically derived atomic orbital exponents. With a method to calculate b, both R₀ and atomic orbital exponents can be experimentally determined through optimized fitting for Cr-O, Cr-S, Mo-O, and Mo-S. In the present study, bond length – valence relationships are found for Cr-O, Cr-S, Mo-O, and Mo-S chemical …

Photochemistry Of A Series Of Weakly Coupled Dinuclear Ruthenium(Ii) Complexes, Latisha Michelle Puckett

Graduate Theses and Dissertations

An improved synthetic method was developed for symmetric ruthenium(II) polypyridine complexes with the form L2Ru(diphen)RuL2. The scope of the reaction was investigated in regards to the ligands, bridging ligands, and starting materials. Several ligands were successful in the synthesis, including 2,2’-bipyridine (bpy), 4,4’-dimethyl-2,2’-dipyridyl (dmb), 1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (dpphen), and 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen). Ligands that did not react to form symmetric dimeric complexes were 2,2’-bipyrazine, bpz, and 2,2’-bipyrimidine, bpm.

Dpp, 2,3-bis(2-pyridyl)-pyrazine, effectively replaced diphen as the bridging ligand to produce (phen)2Ru(dpp)Ru(phen)24+. However, replacing the [Ru(CO)2Cl2]n with Ru(DMSO)4Cl2 did not prove successful. The newly developed synthesis was also applied to the synthesis of …

Low-Level Mercury Causes Inappropriate Activation In T And B Lymphocytes In The Absence Of Antigen Stimulation, K. L. Weigand, J. L. Reno, B. M. Rowley

Journal of the Arkansas Academy of Science

The immune system primarily utilizes two cell types for adaptive immunity: T lymphocytes and B lymphocytes. T lymphocytes are activated when antigen presenting cells (APCs) present antigen to membrane-bound T cell receptors. B lymphocytes are activated when an antigen binds to receptors embedded in the plasma membrane. In both T and B cells this antigen binding crosslinks the receptor complexes and initiates the signal transduction cascade. These cascades frequently consist of a series of intracellular molecules becoming phosphorylated in a step-wise fashion. Once activated, these cells differentiate into effector cells that clear out the stimulating antigen. Mercury, which is a …

Self-Assembly Of Gold Nanosphere Dimers By Inertial Force, George Andrew Christopher Sakhel

Graduate Theses and Dissertations

The morphology and composition of a nanoparticle (NP) play a critical role in determining the NP's properties and function. To date, researchers have created a myriad of NPs of different shapes, sizes, and compositions with interesting attributes and applications ushering a revolution in medicine, electronics, microscopy, and microfluidics.

In this study, gold (Au) nanosphere dimers (NSDs) have been synthesized through a novel self-assembly method. These particles were created from Au NPs mono-dispersed in aqueous solution via a process of centrifugation and capping agent replacement. Au NSDs consist of two Au NPs combined together with minimal gaps between them. Optical spectral …

An Investigation Of The Electronic Coupling In Some Dimeric Ruthenium (Ii) Polypyridine Complexes, Roland Ngebichie Njabon

Graduate Theses and Dissertations

A detailed understanding of respiration at the molecular level requires an understanding of the many electron transfer steps involved in the process. These electron transfer processes are extremely fast and are impossible to measure by simple rapid mixing techniques. In order to get around this problem, scientists have used laser flash photolysis. This technique relies on the fact that under proper conditions, a reactant can be generated by a very short laser pulse. Once generated, the course of the reaction can be monitored by various techniques capable of very rapid time response. Many applications of this methodology rely on the …

On Chlorine Salts: Their Detection, Stability And Implications For Water On Mars And Europa, Jennifer Hanley

Graduate Theses and Dissertations

Chlorine salts (e.g. chlorides, chlorates and perchlorates) are an important factor in the stability of water on the surfaces of planetary bodies. Here we have shown that perchlorate and chlorate salts will lower the freezing point of water, allowing it to be liquid down to ~204 K. These salts will also slow down the evaporation rate, extending the lifetime of the liquid water solution. Chlorine salts have been detected on Mars, which has significant implications for the stability of water and hence its habitability. To study their effects on the stability of water on planetary surfaces, we need to first …

New Effects Of Aging And Lattice Intercalation On Surface Properties Of Titanate Nanobelts, Roger Williams

Graduate Theses and Dissertations

Titanate nanobelts (NBs) have structural characteristics beyond that of clays. Due to a negatively charged lattice matrix of edge-shared TiO6-octahedra, the location of intercalated cations within the interlayer space may dictate the charge-conductions. This environment may in turn govern the lattice-framework's stability and surface properties, based upon our preliminary

data.

On that basis, these nanomaterials have been found in our lab to possess superb biological compatibility that is closely related to the types of the intercalated cations. In addition, a prolonged agitation was proven to enable us to manipulate the titanate NBs' length. In a parallel study, a ripening was …

Microwave Assisted Synthesis Of Chloropentahaptocyclopentadienediphenylphosphinoethaneruthenium(Ii), S. Muthyala, Mark Draganjac

Journal of the Arkansas Academy of Science

No abstract provided.

Molecular Structure Of Pentahaptocyclopentadienebis (Tetrahydrothiophene) Triphenylphosphineruthenium(Ii) Triflate, Paul M. Nave, Mark Draganjac, A. W. Cordes

Journal of the Arkansas Academy of Science

No abstract provided.

Refractive Index Chemical Sensing With Noble Metal Nanoparticles, Phillip Blake

Graduate Theses and Dissertations

Chemical sensing is a key component in modern society, especially in engineering applications. Because of their widespread impact, improvements to chemical sensors are a significant area of research. One class of sensors, plasmonic sensors, is being heavily researched because of their ability to detect low levels of analyte in near real time without destroying the analyte. This work studies a new class of plasmonic sensor that utilizes diffractive coupling to improve sensor performance. Specifically, this work outlines the first study of diffractive coupling sensors with typical nanoparticle shapes. Sensitivity of this new class of sensor is directly compared to typical …

Part I - A Study Of The Formation Of Carbenes By Elimination Of Α-Bromosilanes And Application Toward The Synthesis Of Transition Metal Complexed Quinone Methide Analogs. Part Ii - Development Of Novel 7-Membered Ring Carbene Ligands For Palladium Catalyzed Cross Coupling Reactions., Christian Michael Loeschel

Graduate Theses and Dissertations

In part I, we wish to report our approaches toward transition metal complexed ortho-quinone methide analogs. ortho-Quinone Methides are a class of highly reactive compounds with a wide range of chemical and biological applications. Previously, a stable iron complexed benzannulated 5-membered ring quinone methide analog was reported by Allison and Neal27. Herein, we report our approaches to improve the reactivity of that system by removing benzannulation as well as changing the metal from iron to manganese and rhenium.

Furthermore, a methodological study on generating carbenes under mild conditions by elimination of α-halosilanes and its application towards metal complexed quinone methide …

Stabilization Of Polyvinyl Chloride By Some Conducting Polymers, Amit Shah, Brian C. Berry, Ali U. Shaikh

Journal of the Arkansas Academy of Science

No abstract provided.