Materials Chemistry Commons^™

Preparation And Electrochemical Evaluation Of Mos2/Graphene Quantum Dots As A Catalyst For Hydrogen Evolution In Microbial Electrolysis Cell, Hong-Yan Dai, Hui-Min Yang, Xian Liu, Xiu-Li Song, Zhen-Hai Liang

Journal of Electrochemistry

Microbial electrolysis cell (MEC) is a relatively new bioelectrochemical technology that produces H₂ and meanwhile treats organic wastewater. Cathode hydrogen evolution catalyst plays a key role in MEC. The doping of Graphene Quantum Dots (GQDs) into MoS₂ nanosheets can improve the catalytic activity of MoS₂ by creating abundant defect sites both in the edge plane and the basal plane, as well as enhancing the electrical conductivity. In this paper, using Na₂MoO₄ , cysteine and GQDs as raw materials, a series of MoS₂/GQDs composites were firstly synthesized via hydrothermal method, and then loaded …

Study On Inhibition Of Lithium Dendrite Growth By Mg(No3)2 Additive In Carbonate Electrolyte, Biao Zhang, Yi Shuai, Yu Wang, Na-Chuan Yang, Kang-Hua Chen

Journal of Electrochemistry

In the lithium-sulfurized polyacrylonitrile battery system, the formation and growth of lithium dendrites in the negative electrode seriously deteriorate the charge and discharge performance of the battery. If the growth of lithium dendrites pierces the separator and causes thermal runaway, it will also bring serious damage to the battery, causing potential safety risks. In the carbonate electrolyte that is more conducive to stabilizing the positive electrode sulfurized polyacrylonitrile material, the growth of lithium dendrites is particularly serious. In this paper, magnesium nitrate was added to the carbonate electrolyte to investigate the combined effect of nitrate and magnesium ions on the …

A Preliminary Study On Graphene Film-Metal Composites Prepared By Electrodeposition, Shuang-Juan Liu, Hai-Jing Wang, Jing Guo, Peng-Cheng Wang, Hao Zhou, Cai Meng, Han-Jie Guo

Journal of Electrochemistry

Graphene film (GF) has excellent electrical and thermal conductivity, but low strength and hardness. In order to obtain good comprehensive mechanical properties to improve the practical value of GF, the concept of preparing GF-metal composite materials was proposed. This work was conducted to preliminarily study the feasibility of using electrodeposition method to prepare GF-metal composites. Two kinds of composites, GF-Cu and GF-Cr, were successfully prepared by using GF as the cathode, and pure Cu and DSA (Dimensionally Stable Anode) as the anodes, respectively, with applying DC power externally. Employing certain electrochemical parameters, the cation in the electrolyte moved towards the …

Effect Of Conductive Additives On Electrochemical Performance Of All-Solid-State Li-S Batteries, Dong-Hao Wang, He-Feng Yan, Zheng-Liang Gong

Journal of Electrochemistry

All-solid-state lithium sulfur batteries (ASSLSBs) with inorganic solid electrolytes offer an opportunity to realize both high energy density (lithium metal ~ 3860 mAh·g^-1, sulfur ~ 1675 mAh·g^-1), safety and reliability, via eliminating the polysulfides shuttle effect and flammable liquid electrolyte. However, it still remains a huge challenge for ASSLSBs to achieve high areal active mass loading, high utilization efficiency of the active materials and good cycle stability simultaneously due to the insulating nature of sulfur and Li₂S (conductivities of sulfur and Li₂S are 5×10^-30 S·cm^-1 and 3.6×10^-7 S·cm^{-1 …}

Preparation Of Coo/Rgo@Ni Foam Electrode And Its Electrocatalytic Reduction Of Co2, Qian Guo, Jia-Long Fu, Cheng-Yan Zhang, Chao-Yue Cai, Cheng Wang, Li-Hua Zhou, Rui-Bo Xu, Ming-Yan Wang

Journal of Electrochemistry

The worldwide extensive release of carbon dioxide (CO₂) has caused serious environmental pollution and unprecedented climate change problems. Thus, for the sustainable development of human society, it is very necessary to convert CO₂ to renewable fuels through clean and economical processes. The electrochemical CO₂ reduction reaction (CO₂RR) is regarded as a promising approach for the recycling of carbon resource and the generation of sustainable fuels. However, the slow kinetics and formation of multiple products in CO₂RR hinder its large-scale application. Hence, great research efforts are made to develop electrocatalysts with high product …

From Small Molecules To Infinite Crystals: Probing Noncovalent Interactions Through Vibrational Spectroscopy, Sadisha Nanayakkara

Chemistry Theses and Dissertations

During my four years in the CATCO group supervised by Dr. Kraka, I have been exposed to various topics targeted to address a multitude of chemical problems, broadening our knowledge of modern chemistry research as we know it. In undertaking the age-old problem of understanding the nature of chemical bonding, I could modestly contribute with my work, using in-house tools based on vibrational spectroscopy.

First part of my dissertation is focused on inventing new methods and tools to efficiently investigate chemical bonding, followed by the study of some non-covalent interactions, imperative in catalysis and solid-state chemistry. This includes analysis of …

Doping Of Conjugated Polymers: Preparation, Characterization And Device Fabrication, Kan Tang

Dissertations

Semiconducting conjugated polymers (CPs) as emerging materials for advanced electronic applications such as sensors, OPVs, and OEFTs has become an intriguing research topic in the past decades. It opens a new avenue of “flexible” electronics, which has shown great potential in next-generation electronic devices.

However, due to the nature of CP materials and related solution processing techniques, unlike almost perfectly crystalline silicon materials, CPs in the solid-state often exhibit much lower crystallinity if it is not complete amorphous, which severely hinder the electronic property and optical property of the materials. The crystallinity of CPs in a film is often uniquely …

Vortex-Oriented Ferroelectric Domains In Snte/Pbte Monolayer Lateral Heterostructures, Kai Chang, John W. D. Villanova, Jing-Rong Ji, Souvik Das, Felix Kuster, Salvador Barraza-Lopez, Paolo Sessi, Stuart S. P. Parkin

Physics Faculty Publications and Presentations

Heterostructures formed from interfaces between materials with complementary properties often display unconventional physics. Of especial interest are heterostructures formed with ferroelectric materials. These are mostly formed by combining thin layers in vertical stacks. Here the first in situ molecular beam epitaxial growth and scanning tunneling microscopy characterization of atomically sharp lateral heterostructures between a ferroelectric SnTe monolayer and a paraelectric PbTe monolayer are reported. The bias voltage dependence of the apparent heights of SnTe and PbTe monolayers, which are closely related to the type-II band alignment of the heterostructure, is investigated. Remarkably, it is discovered that the ferroelectric domains in …

Synthesis Of The Diazonium Zwitterionic Polymer/Monomer For Use As The Electrolyte In Polymer Electrolyte Membrane (Pem) Fuel Cells, Josiah Marshall

Electronic Theses and Dissertations

My research goals are to synthesize new zwitterionic perfluorosulfonimide (PFSI) monomer/polymers. They are expected to replace traditionally used perfluorosulfonic acid (PFSA) polymers as the electrolyte in PEM fuel cells. For the PFSI monomer preparation, we designed a nine-step synthesis route. Thus far, I have successfully completed the synthesis of 4- (2-bromotetrafluoroethoxy)-benzenesulfonyl amide, 4-acetoxybenzenesulfonic acid sodium salt, and 4-chlorosulfonyl phenyl acetate. The coupling reaction of 4-(2-bromotetrafluoroethoxy)- benzenesulfonyl amide with 4-chlorosulfonyl phenyl acetate, was troublesome due to slow reaction kinetics and byproducts. Additionally, I did a methodology study for the homopolymerziation of the perfluoro 3(oxapent-4-ene) sulfonyl fluoride monomer. We compared the weight …

Characterization Of Lamellar Liquid Crystal Emulsifiers In Topical Creams Containing A Novel Solvent, Melinda Joanna Sutton

Graduate Theses/Dissertations

Diethylene glycol monoethyl ether (DEGEE) is a promising solvent component in topical cream formulations due to its superior solubilizing abilities with certain active pharmaceutical ingredients. One of the goals of this study is to characterize the effects of pH on the physical and chemical stabilities of topical cream formulations containing particularly high concentrations of DEGEE by characterizing a full topical pH profile of 3.5 – 9.0. The second goal is to evaluate the presence, amount, and characteristics of lyotropic liquid crystals (LLCs), molecularly structured in a lamellar phase, in a model cream emulsion utilizing polarized light microscopy (PLM). The presence …

Comparison Of Chalk Types And Their Ghosting Effects, Felicienne Alexandre, Shoshanna Coon, Kirk Manfredi

Summer Undergraduate Research Program (SURP) Symposium

Chalkboard ghosting is a faint image on a chalkboard's surface after writing is erased. Many types of chalk leave a positive image, while the Crayola An-du-septic Anti-dust chalk leaves a negative image. To better understand what cause the ghosting effects, two different types of Crayola chalk (regular and anti-dust) were investigated. Raman spectroscopy and infrared (IR) spectroscopy were used to determine the majority material the chalk was made of, by comparison with pure substances. To identify the organic compound binders holding the chalk sticks together, pulverized chalk was immersed in 40 mL of toluene for at least 30 minutes. After …

Fabrication Of Electrospun Nanofiber Composite Of G-C3n4 And Au Nanoparticles As Plasmonic Photocatalyst, Dipendu Saha, Pasquale Gismondi, Kurt W. Kolasinski, Samantha L. Shumlas, Sylvie Rangan, Babak Eslami, Amy Mcconnell, Taevaughn Bui, Kayla Cunfer

Chemistry Faculty Publications

In this research, we have fabricated a composite nanofiber mat of plasmonic photocatalyst consisting of g-C3N4, gold nanoparticles (AuNPs) and random nanofibers of polyvinylidene fluoride (PVDF) by electrospinning. The structure and chemical properties of the nanofiber mat were investigated in detail by ESEM, TEM, AFM, XPS, FTIR, XRD, TGA, PL spectroscopy and UV-Vis reflectance spectra. Imaging of the composite map confirmed that the fiber diameter was in the range of 100-400 nm with the g-C3N4 size in the range of 2-8 μm. Backscattered (Zcontrast) electron imaging in ESEM revealed that the AuNP particle size is in the range of 60-160 …

Designing Atomic Edge Structures In 2d Transition Metal Dichalcogenides For Improved Catalytic Activity, Raymond R. Unocic, Xiahan Sang, Guoxiang Hu, Victor Fung, Jingsong Huang, Matthew G. Boebinger, Kai Xiao, Panchapakesan Ganesh

Publications and Research

Designing new materials for functional applications depends upon our ability to understand and correlate the materials structure and chemistry to functional material properties. This is even more important for two-dimensional (2D) materials where thicknesses are on the order of a single atom to a few-atomic layers; therefore, any structural or chemical modification at these length scales can have a profound effect on modifying physical and chemical properties. 2D transition metal dichalcogenides (TMDs) such as MoS2 have emerged as a promising catalyst for the hydrogen evolution reaction with defects such as vacancies and edges being linked to high catalytic active sites …

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …

The Development And Application Of Instrumental Methods For The Identification Of Materials And Processes Used In The Manufacture Of Orotone, Hand-Colored Orotone, And Silvertone Photographs, Ivanny Jeannette Jácome-Valladares

Dissertations and Theses

Orotone photographs are positive photographic images on glass with a gold-colored metallic coating or backing. Although the materials and process used in the production of orotones have been previously documented, there is limited published scientific research on the subject. This study focused on expanding those published works by analyzing a greater number of photographs, including eleven orotones, four hand-colored orotones, two silvertones, and one uncoated orotone. The photographs, dating from the early to mid-20^th century, were from the University of Washington (UW) Libraries' collection, except for one orotone that was from the Portland Art Museum.

X-ray Fluorescence (XRF) spectroscopy, …

Photovoltages In Polycrystalline Mosaic Solar Cells, Steluta A. Dinca, Eric A. Schiff

Chemistry - All Scholarship

In some thin-film solar cells the light-absorbing layer is a mosaic of crystalline grains whose boundaries run from the back to the front of the cell. We used the semiconductor modeling software Sesame to do numerical calculations of the optoelectronic properties of such cells assuming that recombination of minority photocarriers occurs primarily at the grain boundaries. The work complements analytical results for diffusion-limited recombination at grain boundaries and dislocations. We chose idealized n-CdS/p-CdTe solar cells for illustration. We find that the open-circuit voltage, V_oc, under illumination declines logarithmically with increasing ratio D/θ², where D is the …

Design Of Antioxidant Monomer, Augustine Osilamah Yusuf

Masters Theses & Specialist Projects

Reactive oxygen species such as hydrogen peroxide are present at the sites of inflammation in the body. Degradable polymeric nanoparticles have shown great promise in a range of biomedical applications which include preferential delivery of therapeutics to such inflamed sites. We are working towards a new class of materials expected to have tunable degradation rates in the presence of hydrogen peroxide. These new materials consist of three parts: degradable linkages, antioxidant groups, and unreactive filler monomers such as methylmethacrylate. We have synthesized a polymerization initiator with a degradable linkage, and we have shown that using this initiator to synthesize another …

Phase-Field Modeling Of The Polymer Membrane Formation Process For Micro- And Ultra-Filtration, Michael Rosario Cervellere

Graduate Theses and Dissertations

Porous polymer membrane filters are widely used in separation and filtration process. Micro- and ultra-filtration membranes are commonly used in biopharmaceutical applications such as filtering viruses and separating proteins from a carrier solution. The formation of these membrane filters via phase inversion is a complex and interconnected process where varying casting conditions can have a wide variety of effects on the final membrane morphol- ogy. Tailoring membrane filters for specific performance characteristics is a tedious and time consuming process. The time and length scales of membrane formation make it extremely difficult to experimentally observe membrane formation. Modeling the membrane formation …

Harnessing Surface Chemistry And Instabilities In Silicone Elastomers To Synthesize Adaptive Systems With Mechanically Tunable Surface Properties And Functionality, Ali Jamal Mazaltarim

Department of Chemistry: Dissertations, Theses, and Student Research

Material interfaces are of critical importance to numerous fields, including nanomaterials, electronics, microfluidics, synthesis, bioanalysis, pharmaceuticals, and catalysis, and they have been extensively researched. The materials used in these fields are often rigid/hard (such as silicon wafers) resulting in static surface properties. Consequently, the chemical/morphological properties of a surface may be modified using synthetic or mechanical means to tailor the interfacial properties of a material (i.e., surface energy, adhesion, topography, and reactivity). Recently, emphasis has been placed on designing dynamic materials with adaptive interfacial properties that respond to a variety of environmental stimuli. To this end, the surface chemistry and …

Metal-Assisted Catalytic Etching (Mace) For Nanofabrication Of Semiconductor Powders, Kurt W. Kolasinski

Chemistry Faculty Publications

Electroless etching of semiconductors has been elevated to an advanced micromachining process by the addition of a structured metal catalyst. Patterning of the catalyst by lithographic techniques facilitated the patterning of crystalline and polycrystalline wafer substrates. Galvanic deposition of metals on semiconductors has a natural tendency to produce nanoparticles rather than flat uniform films. This characteristic makes possible the etching of wafers and particles with arbitrary shape and size. While it has been widely recognized that spontaneous deposition of metal nanoparticles can be used in connection with etching to porosify wafers, it is also possible to produced nanostructured powders. Metal-assisted …