Physical Chemistry Commons^™

Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing

Honors Scholar Theses

The Toxic Substances Control Act (TSCA) is the central form of chemical regulation existent in the United States today, yet scientists are often unaware or uncertain of its provisions. Violations of TSCA by unknowing chemists set industry and government unnecessarily at odds. A lecture on TSCA was developed for undergraduate students that uses the concept of green chemistry to promote interest and incentivize learning. Green chemistry methods are cleaner and less wasteful than traditional chemical ones, and many companies using them are at the forefront of technological innovation. The lecture explains both green chemistry and TSCA, includes company case studies, …

Analysis And Comparison Of The Photodecomposition Reaction Of Methanol On Ceo2 Impregnated Tio2 Surfaces Versus Bare Tio2 Surfaces, Christopher A. Estes

Master of Science in Chemical Sciences Theses

Titanium dioxide (TiO₂) has been well-studied primarily due to its unique photocatalytic activity. Different preparation techniques have been developed to increase its photocatalytic activity by various means, including simply increasing the surface area, changing the makeup of the framework, and modifying the surface with a dopant. This study focuses on the effect cerium oxide (CeO₂) has on the photocatalytic activity of TiO₂ by depositing CeO₂ on the TiO₂ surface. Methanol is used as a probe reactant for these experiments due to its wide use in heterogeneous catalysis research and the limited products that …

Investigations Of The Photocatalytic Activity And Self-Cleaning Properties Of Polyhedral Oligomeric Silsesquioxane (Poss) Containing Titania Thiol-Ene Films, Lacrissia Unsonta Jefferson

Dissertations

In this document the film composition, self-cleaning aspect, photocatalytic efficiency, and methods employed to analyze a novel photocatalytic titania-containing thin film was evaluated. A primary objective of this research project was to assess the conditions required to achieve a stable titania dispersion for the photocatalytic coating and to determine the extent to which the presence of additives contributes to this process. Modified titania dispersions were prepared and characterized via dynamic light scattering (DLS), transmission electron microscopy (TEM), fourier transmission infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Characterization details of the previous focus on the influence of polyhedral oligomeric silsesquioxane (POSS) …

The Requisite Electronic Structure Theory To Describe Photoexcited Nonadiabatic Dynamics: Nonadiabatic Derivative Couplings And Diabatic Electronic Couplings, Joseph E. Subotnik, Ethan Alguire, Qi Ou, Brian R. Landry, Shervin Fatehi

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Conspectus

Electronically photoexcited dynamics are complicated because there are so many different relaxation pathways: fluorescence, phosphorescence, radiationless decay, electon transfer, etc. In practice, to model photoexcited systems is a very difficult enterprise, requiring accurate and very efficient tools in both electronic structure theory and nonadiabatic chemical dynamics. Moreover, these theoretical tools are not traditional tools. On the one hand, the electronic structure tools involve couplings between electonic states (rather than typical single state energies and gradients). On the other hand, the dynamics tools involve propagating nuclei on multiple potential energy surfaces (rather than the usual ground state dynamics).

In this …

Chemically Accurate Calculations Of Rate Constants Of Spin Trap-Hydroxyl Radical Addition Reactions, Hayden B. Short

Undergraduate Honors Theses

The DMPO type spin trap 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) and the exceptionally similar spin trap 2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-l-oxide (EMPO) are widely studied in computational and theoretical works. This particular study examines the addition reactions that both these molecules undergo with the carcinogenic hydroxyl radical. This work used a relatively new approximation method, called the correlation consistent composite approach or ccCA, for carrying out quantum mechanical calculations to give the free energies of the products and reactants of the reactions. The free energies are to be used to extrapolate the rate constants of the reactions from the Arrhenius equation. Though both the spin traps …

Inertial Force-Driven Synthesis Of Near-Infrared Plasmonic Nanosphere Composites: Physicochemical Characterizations, Joseph Noel Batta-Mpouma

Graduate Theses and Dissertations

Near-infrared (NIR) responsive nanoparticles (NPs) like gold nanorods (GNRs) are important in biomedical fields because of their transparency for biological tissues. Although GNRs are sought after as contrast agents for theranostics in cancer studies, capping ligands like cetyltrimethylammonium bromide (CTAB) for the GNR synthesis are toxic for biological tissues. The need for an alternative to toxic GNRs is of interest to alleviate the problem.

This work aimed to optimize the synthesis of NIR responsive nanosphere composites (NSCs) by inertial force (g-force) using colloidal gold NPs as model, elucidate the mechanism for the NSC formation, and study their detailed physicochemical characteristics. …

Recent Research Progress For Non-Pt-Based Oxygen Reduction Reaction Electrocatalysts In Fuel Cell, Ping Song, Ming-Bo Ruan, Jing Liu, Guang-Jun Ran, Wei-Lin Xu

Journal of Electrochemistry

The expensive Pt-based catalyst suffers from its susceptibility to time-dependent drift, methanol crossover, and carbon monoxide (CO) deactivation, which will block the large-scale commercial application of fuel cells. It is, therefore, necessary to develop efficient, low-cost, highly stable non-precious metal oxygen reduction reaction (ORR) catalysts with high catalytic performance. Here, we will pay attention to the research progress of non-precious metal and heteroatom-doped (N, B, P, S, F) metal-free ORR catalysts. Importantly, we mainly focus on the work developed by Xu’s group with the Fe-based non-precious metal and F/NF-doped metal-free ORR catalysts. The purpose of these works is to improve …

Research Progress Of Mn-Based Lithium-Rich Cathode Materials For Li-Ion Batteries, Luo-Zeng Zhou, Qun-Jie Xu, Wei-Ping Tang, Xue Jin, Xiao-Lei Yuan

Journal of Electrochemistry

With rapid development of new energy industry like electric vehicles and energy storage station, these fields highly demand the next generation of high performance Li-ion battery systems with stronger energy density, higher power density, and longer cycling life. Lithium-rich Mn-based cathode materials, xLi₂MnO₃·(1-x)LiMO₂(M=Mn, Co, Ni...), have become the hot topic and drawn attentions of scholars worldwide because of their high reversible capacity exceeding 240 mAh·g^-1, excellent electrochemical properties, and low cost, which makes them most promising cathode material candidates for next Li-ion battery system. The cathode material Li[Li_0.2Mn_0.54Ni …

Preparation And Properties Of Binary Oxides CoXCr1-XO3/2 Electrocatalysts For Oxygen Evolution Reaction, Tai-Lai Yang, Wen-Yan Dong, Hui-Min Yang, Li Zhang, Zhen-Hai Liang

Journal of Electrochemistry

Binary metal mixed oxides of Co and Cr with nominal compositional formulas, Co_xCr_1-xO_3/2 (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0), were obtained by thermal decomposition method. The morphologies, crystal forms and valence states of the catalyst powders were analyzed by SEM, XRD and XPS, respectively. And the electrochemical properties, overpotentials and stabilities of Co_xCr_1-xO_3/2 electrodes for oxygen evolution reaction (OER) in an alkaline solution were evaluated by linear sweep voltammetry (LSV), staircase voltammetry and chronoamperometry, respectively. The results indicated that the mixtures of Co₃O₄ and eskolaite-Cr_{2 …}

Synthesis And Electrochemical Properties Of Cnts/V2O5 Hollow Microspheres, Liang Hao, Lai-Fa Shen, Jie Wang, Jia-Jia Zhu, Xiao-Chen Zhao, Xiao-Gang Zhang

Journal of Electrochemistry

The carbon nanotubes/vanadium oxides (CNTs/V₂O₅) hollow microspheres (VOC) were prepared via solvothermal process. The effects of the ratio for CNTs to V₂O₅ on the morphologies, structures and electrochemical performances were systemically investigated. The results indicate that CNTs dramatically enhanced the rate performances of VOC composite electrodes. When the ratio of CNTs is 7.1%, the VOC composite electrode exhibited the best electrochemical performance, which delivered a specific capacitance of 346 F·g^-1 at 0.5 A·g^-1 and maintained 75% at 8 A·g^-1 in 5 mol L^-1 LiNO₃. A hybrid capacitor …

Electrochemical Performance And Reaction Mechanism Of Li3Fe2(Po4)3/C Cathode Material, Yong Xie, Gui-Ming Zhong, Zheng-Liang Gong, Yong Yang

Journal of Electrochemistry

The cathode material of carbon coated Li₃Fe₂(PO₄)₃ (Li₃Fe₂(PO₄)₃/C) is successfully prepared by sol-gel method and ball-milling carbon coating technique. The cathode material is characterized by XRD, SEM, TEM, and in-situ XAFS techniques. XRD results indicate that the as prepared Li₃Fe₂(PO₄)₃ is of high purity and single phase, and has monoclinic structure with space group of P21/n. Electrochemical measurements show that the carbon-coated material is able to deliver a high initial discharge specific capacity of 128.6 mAh·g^-1 in …

Electrochemical Performance Of Coal2O4-Coated Lini1/3Co1/3Mn1/3O2, Ji-Jun Cai, Wang-Jun Cui, Bing Li, Yang-Yang Yu, Jin-Bao Zhao

Journal of Electrochemistry

A method to improve the electrochemical performance of LiNi_1/3Co_1/3Mn_1/3O₂ for high voltage lithium-ion battery by CoAl₂O₄ coating was present in this work. The effects of CoAl₂O₄ coatings on the structure and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were investigated in detail. The results show that CoAl₂O₄ forms a thin layer of 8 nm on the surface of LiNi_1/3Co_1/3Mn_1/3O₂ without destroying the structure of the core material. The CoAl₂O₄-coated LiNi_1/3Co_1/3Mn_1/3O …

Porous Co3O4 Hollow Nanospheres Cathode Catalyst For High-Capacity And Long-Cycle Li-Air Batteries, Tong Liu, Na Li, Qing-Chao Liu, Xin-Bo Zhang

Journal of Electrochemistry

In this paper, a high specific surface area of porous Co3O4 hollow nanospheres was successfully synthesized via hydrothermal carbonization at 140 °C, followed by calcination using cobalt nitrate hexahydrate (Co(NO3)2·6H2O), hexamethylenetetramine (HMT), sucrose, and sodium citrate (Na3C6H5O7). The porous Co3O4 hollow nanospheres consisted of nanoparticles with high specific surface area of mesoporous structure, and could provide active reaction sites for OER and ORR. When used as lithium-air battery cathode catalyst, the Co3O4/Super P (SP) electrode exhibited excellent cycle performance, resulting in high capacity and long life of lithium-air batteries.

Response Characteristics Of Solution-Gated Graphene Field Effect Transistors To Buffer Solution Ph And Concentration, Xiao-Wei Du, Ji Cheng, Hui Guo, Qing-Hui Jin, Jian-Long Zhao

Journal of Electrochemistry

High-sensitivity and low-noise solution-gated graphene field effect transistors (SGFETs) were fabricated using chemical vapor deposition (CVD) graphene as a channel material, and their response characteristics to concentration and pH of phosphate buffered saline (PBS) were measured. The minimum conductance point shifted to left with increasing concentration, and the offset showed a linear relationship with the natural logarithm of concentration. While, the minimum conductance point shifted to right with increasing pH, and the offset showed a linear relationship with pH. The research on these response characteristics may give proper guidance to SGFETs’s application.

Electrodeposition Of Al-Mg Alloys From Acidic Alcl3-Emic-Mgcl2 Room Temperature Ionic Liquids, Rostomali M., P. Abbott Andrew, S. Ryder Karl

Journal of Electrochemistry

Electrodeposition of aluminium-magnesium alloys have been carried out onto platinum and copper cathodes from Lewis acidic aluminium(III) chloride-1-ethyl-3-methylimidazolium chloride ionic liquid containing magnesium(II) chloride by constant current and constant potential methods at room temperature. Magnesium content in the deposited alloy increases with increasing MgCl₂ concentration in the ionic liquid and with increasing cathodic current density. The influences of various experimental conditions on electrodeposition and the morphology of the electrodeposited layers have been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDAX). On increasing the deposition current densities the dense, bright, adherent …

Syntheses And Electrochemical Performances Of Li4Ti5O12 Anode Materials For Lithium Ion Battery, Yong-Long Zhang, Xue-Bu Hu, Yao-Qiong Wang, Dong-Hai Huang

Journal of Electrochemistry

Series of spinel lithium titanate (Li₄Ti₅O₁₂) materials were synthesized by one-step solid-state reaction using lithium acetate and TiO₂ as raw materials under different temperatures (750/800/850 °C) and atmospheres (N₂/air). The as-prepared Li₄Ti₅O₁₂ materials were investigated by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, cyclic voltammotry and charge-discharge test to analyze their crystal structures, microstructures and electrochemical performances. The results show that the Li₄Ti₅O₁₂（L-800N）material obtained at 800 °C under nitrogen atmosphere exhibited better electrochemical performance and smaller particle size. The initial …

A Platinum-Hydrogen Reference Micro-Electrode For All Vanadium Redox Flow Battery, Zhi-Bin Lin, Yan-Qing Dong, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

A platinum-hydrogen reference micro-electrode was made with electroplating Pd on the surface of Pt wire and then coating anion membrane material. This reference electrode was built-in the porous electrode of the all vanadium redox flow batteries (VRFB), and monitored the charging /discharging and self-discharging of the VRFB. The results indicated that the capacity fading of VRFB occurred due to the graduate reduction of V(IV) active species in the electrolyte and the accumulation of V(V) in the positive electrode, leading to nonequilibrium of active species between the positive and negative electrodes.

Electrochemical Conversion Reactions And Their Applications For Rechargeable Batteries, Ting Li, Han-Xi Yang

Journal of Electrochemistry

Electrochemical conversion reactions have received considerable interest as a new redox mechanism for constructing high capacity electrodes of rechargeable batteries. Without strict restrictions on the crystalline structure of the host lattice and the size of the associated ions, conversion reactions can take place in a variety of different metal compounds with different metal cations and deliver much higher reversible capacities through full utilization of all the oxidation states of the transition-metal compounds, opening up a new avenue for developing high capacity materials of rechargeable batteries. This paper briefly reviews the state of the art and challenges of conversion electrodes and …

Researches On In-Situ And Ex-Situ Characterization Techniques In Lithium Batteries, Wen-Jun Li, Jie-Yun Zheng, Lin Gu, Hong Li

Journal of Electrochemistry

Electrochemical performance of Lithium batteries is directly linked to interfacial transports, reactions and storing behaviors of electrons and ions at bulk-surface interfaces. It is extremely important to conduct evolution studies from atomic level to macro level in electron structures, crystal structures, microstructures and morphologies, chemical compositions and physical properties of battery materials at equilibrium and nonequilibrium in order to understand various structure-performance relations in lithium ion batteries. Advanced in-situ and ex-situ characterization techniques have been used widely to clarify scientific and technological problems in lithium batteries. This paper summarizes our efforts on battery researches using various experimental techniques, including in …

Unraveling Structures Of Protection Ligands On Gold Nanoparticle Au68(Sh)32, Wen Wu Xu, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

New low-energy atomic structures of the thiolate-protected gold nanoparticle Au₆₈(SH)₃₂ are uncovered, where the atomic positions of the Au atoms are taken from the recent single-particle transmission electron microscopy measurement by Kornberg and co-workers, whereas the pattern of thiolate ligands on the gold core is attained on the basis of the generic formulation (or rule) of the “divide and protect” concept. Four distinct low-energy isomers, Iso1 to Iso4, whose structures all satisfy the generic formulation, are predicted. Density-functional theory optimization indicates that the four isomers are all lower in energy by 3 to 4 eV than the …