Materials Chemistry Commons^™

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 …

Research Progress Of Si-Based Anode Materials For Lithium-Ion Batteries, Ding-Qiong Chen, Yang Yang, Qiu-Li Li, Jin-Bao Zhao

Journal of Electrochemistry

Owing to its high theoretical specific capacity (4200 mAh·g^-1), silicon is a promising candidate to replace graphite as the anode in lithium ion batteries (LIBs). However, low intrinsic electric conductivity and dramatic volume change (~ 300%) during the process of lithiation and delithiation result in electrode pulverization and capacity loss with cycling, accordingly, the application of silicon as an anode in LIBs has been severely hindered. We will discuss the structure of silicon electrode including synthesis of Si-based composites，the selection of binder for silicon and the fabrication of binder-free Si-based electrode, as well as the electrolyte additive to …

Research Progress In Cycle Stability Of Silicon Based Li-Ion Battery Anodes, Ze-Liang Guo, Hui Wu

Journal of Electrochemistry

Silicon(Si), with the highest specific capacity currently known, is a promising anode material for Li-ion battery. However, in the charging and discharging process, with Li atoms inserting into and breaking out of the Si crystal lattices, the Si anode undergoes enormous volume expansion and contraction, ending in pulverization. The fact that the specific capacity of bulk Si anodes drop quickly is a challenging problem. In this review, we summarize recent progresses in Si anode. We concern about the nanostructure of silicon, cooperation of silicon with other additives and macrostructure design of anodes. We discuss strengths and shortcomings of different methods, …

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 …}

Research And Application Of Key Materials For Sodium-Ion Batteries, Yong-Chang Liu, Cheng-Cheng Chen, Ning Zhang, Liu-Bin Wang, Xing-De Xiang, Jun Chen

Journal of Electrochemistry

Sodium-ion batteries (SIBs) have been considered as a potential large-scale energy storage technology owing to the abundance, wide distribution, and low price of sodium resources. However, the larger and heavier sodium ion as compared to lithium ion makes it difficult to identify appropriate electrode materials with the capability for fast and stable sodium-ion insertion/extraction. Furthermore, the optimization of electrolyte, the matching of cathode and anode materials, and the construction of sodium-ion full batteries with high-performance, high-safety, and low-cost are urgently needed in order to make SIBs commercially available. This review summarizes the up-to-date research progresses in key materials (including cathode, …

Electrochemical Performance Of Crystalline Li12Si7 As Anode Material For Lithium Ion Battery, Ya-Xiong Yang, Rui-Jun Ma, Ming-Xia Gao, Hong-Ge Pan, Yong-Feng Liu

Journal of Electrochemistry

Crystalline Li₁₂Si₇ is successfully synthesized by heating the mixture of LiH and Si with a molar ratio of 12:7, which avoids the huge difference of the melting points between Li and Si. The electrochemical performance and lithium storage mechanism of the as-prepared Li12Si7 are studied in this work. It is found that only a change in cell volume takes place without a phase change during the lithiation/delithiation of Li₁₂Si₇ at a voltage range of 0.02 ~ 0.6 V, exhibiting a solid-solution lithium storage mechanism. Such a lithium storage process effectively retards the volume effect …

Solvothermal Preparation And Characterization Of Superstructures Of Nanoscopic Cds And Cdse, Tetyana Levchenko

Electronic Thesis and Dissertation Repository

Micrometer-sized superparticles, self-assembled from metallic or semiconducting nanoclusters, can be used as convenient building blocks for preparing functional materials, utilizing the electronic and photophysical properties resulting from the quantum confinement as well as from the coupling between individual nanoscopic constituents.

This research aimed at developing a novel approach utilizing the conversion of a cadmium phenylchalcogenolate precursor (Me₄N)₂[Cd(EPh)₄] (where E = S or Se) under solvothermal conditions for the preparation of nanoscopic CdE, including both crystalline superlattices of large discrete nanoclusters and superstructures with more complex morphology. In particular, 3D cubic superlattices of molecular CdS …

Effects Of Sintering Parameters On The Microstructure And Tensile Properties Of In Situ (Ti5si3 + Tibw)/Ti6al4v Composites With Two-Scale Network Architecture, Yang Jiao, L. J. Huang, L. Geng

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

No abstract provided.

In Situ Ion Exchange In A Micro-Porous Transition Metal Silicate Framework, Jason M. Lively

Masters Theses & Specialist Projects

Ion selectivity of minerals has traditionally been utilized in industry as a catalyst, metal separation, and environmental reclamation/sequestration tool. There is an increased interest in understanding ion selectivity mechanisms of micro-porous minerals and mineral-like structures and how they can be applied in various industries: environmental and, potentially, pharmaceutical. This study seeks to understand the ion exchange mechanisms in micro-porous zirconosilicates using time-resolved Raman spectroscopy and X-ray diffraction. The thesis material was exchanged with H+, Na+, K+, and Cs+ in order to better understand structural changes as well as the influence of the H+-bonding during the exchange process. It is hypothesized …

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 …

Dealloying Behavior Of Nico And Nicocu Thin Films, Benjamin Peecher, Jennifer R. Hampton

Faculty Publications

Porous metals and alloys, such as those fabricated via electrochemical dealloying, are of interest for a variety of energy applications, ranging from their potential for enhanced catalytic behavior to their use as high surface area supports for pseudocapacitor materials. Here, the electrochemical dealloying process was explored for electrodeposited binary NiCo and ternary NiCoCu thin films. For each of the four different metal ratios, films were dealloyed using linear sweep voltammetry to various potentials in order to gain insight into the evolution of the film over the course of the linear sweep. Electrochemical capacitance, scanning electron microscopy, and energy dispersive X-ray …

Metal-Organic Hybrid Nanocomposites For Energy Harvesting Applications, Thulitha Madawa Abeywickrama

Masters Theses & Specialist Projects

Various synthetic methods have been developed to produce metal nanostructures including copper and iron nanostructures. Modification of nanoparticle surface to enhance their characteristic properties through surface functionalization with organic ligands ranging from small molecules to polymeric materials including organic semiconducting polymers is a key interest in nanoscience. However, most of the synthetic methods developed in the past depend widely on non-aqueous solvents, toxic reducing agents, and high temperature and high-pressure conditions. Therefore, to produce metal nanostructures and their nanocomposites with a simpler and greener method is indeed necessary and desirable for their nano-scale applications. Hence the objective of this thesis …

Development Of Dihydrochalcone Functionalized Gold Nanoparticles For Augmented Antineoplastic Activity, Jason N. Payne

Masters Theses & Specialist Projects

Phloridzin, an antidiabetic and antineoplastic agent usually found in fruit trees, is a dihydrochalcone constituent that has a clinical/pharmaceutical significance as a sodiumglucose linked transport 2 (SGLT2) inhibitor. Phloridzin never experienced widespread clinical usage in the pharmaceutical market due to its side effects and poor bioavailability when compared to other antidiabetic therapeutics. The poor bioavailability is primarily attributed to the degradation of the glycosidic bond of the phloridzin, resulting in the formation of phloretin, the aglycone of phloridzin and glucose. While phloretin displays a reduced capacity of SGLT2 inhibition, this nutraceutical shows enhanced antineoplastic activity in comparison to phloridzin. Gold …

Photodynamic Killing Of Human Cancer Cells With Smart Photosensitizer Materials And An Endoscopic Implement For Singlet Oxygen Delivery, Mihaela N. Minnis

Dissertations, Theses, and Capstone Projects

The thesis describes progress on probe tips for a microoptic device for the precise delivery of the components necessary for photodynamic therapy (PDT) in a highly localized and controllable fashion. The thesis also summarizes results of a photosensitized oxidation study. The work focused on i) developing a photoactive fluoropolymer surface that will release sensitizer drug molecule for use in PDT, ii) designing new probe tips surfaces for use as sensitizer support for a microoptic PDT device, iii) exploring strategies for covalent attachment of sensitizers and model compounds to Teflon/PVA surfaces with the aim of being coupled with our microoptic device, …

Development Of New Radiolabeling Methods And Insights On Ionizing Radiation Interactions With Nanoparticles, Travis Shaffer

Dissertations, Theses, and Capstone Projects

Nanoparticles are often combined with radionuclides for various applications, ranging from waste remediation to imaging and therapy in the medical field. The overarching aim of this body of work is two-fold. The first aim is development of new radiolabeling methods for various nanoparticles that allow stable attachment of a variety of imaging and therapeutic radionuclides. The second portion more fully describes mechanisms of interaction between ionizing radiation and nanoparticles.

The following advancements will be presented in this dissertation: i) a new radiolabeling method for silica and silica-based nanoparticles that does not require the use of specific chelators, with both radiochemical …

Probing The Structure And Photophysics Of Porphyrinoid Systems For Functional Materials, Christopher D. Farley

Dissertations, Theses, and Capstone Projects

Porphyrins (Pors) and their many cousins, including phthalocyanines (Pcs), corroles (Cors), subphthalocyanines (SubPcs), porphyrazines (Pzs), and naphthalocyanines (NPcs), play amazingly diverse roles in biological and non-biological systems because of their unique and tunable physical and chemical properties. These compounds, collectively known as porphyrinoids, can be employed in any number of functional devices that have the potential to address the challenges of modern society. Their incorporation into such devices, however, depends on many structural factors that must be well understood and carefully controlled in order to achieve the desired behavior. Self-assembly and self-organization are key processes for developing these new technologies, …

Sustainable Molecular Gelators: Beta-D-Glucoside Derived Structuring Agents And Their Material Application, Julian R. Silverman

Dissertations, Theses, and Capstone Projects

Though molecular gelators may by synthesized and formulated into gels following a variety of methods, it should serve that the most valued methods may utilize renewable and waste resources and follow sustainable procedures. Molecular gelators are systems capable of structuring liquids into solid-like materials and they represent a class of surfactant and amphiphilic materials which posses the capability to be not only useful in their ability to form gels, but multifunctional in the ability to respond smartly to a variety of stimuli. Thus there is an interest in the development of sustainable molecular gelators capable of being applied to applications, …

Nanostructured Air Electrodes And Electrochemical Reaction Mechanism Studies For Sodium-Oxygen Batteries, Hossein Yadegari

Electronic Thesis and Dissertation Repository

Alkali metal-O₂ batteries, i.e. Li- and Na-O₂, are considered as the next generation of energy saving technologies with potential application in electric transportation. The high theoretical energy density in these cells is related to the use of high energy alkali metals as negative and oxygen as the positive electrode materials. The performance of alkali metal-O₂ cells is highly dependent on the positive electrode material, where oxygen reduction and evolution reactions take place. Besides, the primary products of oxygen reduction reaction in these cells are typically metal oxides, which are insoluble in nonaqueous electrolytes, resulting in accumulation …

Fabricating And Characterizing Chalcogenide Thin Films As Light Absorbing Layers In Solar Cells, Daniel Vaccarello

Electronic Thesis and Dissertation Repository

Solar cell development has been a focus in energy research, with light-absorbing layers as the key theme. Copper indium disulphide (CuInS₂) and copper zinc tin sulphide (Cu₂ZnSnS₄ or CZTS) have energy band gaps that are optimal for solar energy conversion. New preparation methods have been developed with practicality, safety, and low costs in mind. The one-pot method developed in this thesis group has been utilized to create nanocrystals that can be used to absorb light and generate current. The use of low temperatures and minimalistic reaction conditions has led to the production of CIS and …

Relating Side Chain Organization Of Pnipam With Its Conformation In Aqueous Methanol, Debashish Mukherji, Manfred Wagner, Mark D. Watson, Svenja Winzen, Tiago E. E. De Oliveira, Carlos M. Marques, Kurt Kremer

Chemistry Faculty Publications

Combining nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and μs long all-atom simulations with two million particles, we establish a delicate correlation between increased side chain organization of PNIPAm and its collapse in aqueous methanol mixtures. We find that the preferential binding of methanol with PNIPAm side chains, bridging distal monomers along the polymer backbone, results in increased organization. Furthermore, methanol–PNIPAm preferential binding is dominated by hydrogen bonding. Our findings reveal that the collapse of PNIPAm is dominated by enthalpic interactions and that the standard poor solvent (entropic) effects play no major role.