Physical Chemistry Commons^™

Photoelectrochemical Studies On Non-Noble Metal Based Catalysts Towards Tandem Solar Water Splitting, Arun Siddarth Sridhar

Dissertations

Photoelectrochemical (PEC) water splitting makes direct use of solar energy incident on semiconductor photoelectrodes, and it is a convenient, economic option to produce high purity hydrogen at low temperatures. The use of multiple light absorbers can increase overall solar energy utilization and provide a solution to the trade-off between overall band gap and band edge positioning of photoelectrodes specific to solar water oxidation and water reduction. The study of non-noble metal based catalysts for hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) are essential for economic practical commercialization of photo-electrolyzers. This dissertation focuses on the use of a variety …

Computational Modeling Of Electronically Excited States In Cobalamin-Dependent Reactions., Brady D. Garabato

Electronic Theses and Dissertations

The current understanding of the photolytic properties of Vitamin B12 derivatives or cobalamins are summarized from a computational point of view. The focus is on two non-alkylcobalamins, cyanocobalamin (CNCbl) and hydroxocobalamin (HOCbl), two alkylcobalamins, methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), as well as the stable cob(II)alamin radical. Photolysis of alkylcobalamins involves low-lying singlet excited states where photo-dissociation of the Co-C bond forms singlet-born alkyl/cob(II)alamin radical pairs (RPs). Potential energy surfaces (PESs) of low-lying excited states as functions of both axial bonds provide the most reliable tool for analysis of photochemical and photophysical properties. Due to the size limitations associated with the …

Surface Reaction And Diffusion Kinetics In Semiconducting Metal Oxide Film Gas Sensors, Aravind Reghu

Electronic Theses and Dissertations

Chemiresistive metal oxide gas sensors based on materials such as SnO₂, ZnO, and TiO₂, have been investigated extensively by many researchers for a wide range of applications. The band bending model, based on the surface chemistry of highly reactive ionosorbed species (O₂^- or O^-) and the semiconducting material properties of SnO₂, TiO₂ and ZnO, adequately predicts the dependence of the change in sensor conductivity (Δσ) as a function of target gas pressure and temperature. However, the band bending model is not applicable to gas sensors based on reducible oxides …

Singlet Oxygen Oxidation Of Guanine, 9-Methylguanine And Guanine-Cytosine Base Pair: Dynamics And Kinetics Revealed By Parallel Gas- And Solution-Phase Experiments And Computations, Wenchao Lu

Dissertations, Theses, and Capstone Projects

Singlet oxygen (¹O₂) oxidatively generated damage of DNA gives rise to mutagenesis, carcinogenesis, and cellular death. Guanine is the most susceptible DNA target of ¹O₂. The related process has been studied over three decades but the mechanism has remained elusive. My thesis research has focused on reaction mechanism, dynamics and kinetics of ¹O₂ oxidation of guanine, 9-methylguanine and guanine-cytosine base pair, from the gas-phase bare ions, through hydrated clusters, to aqueous solution. Various techniques have been adapted in the work, including ¹O₂ generation and detection, guided-ion beam tandem mass …

Computational Study Of Lawesson’S Reagent Mediated Fluorenone Dimerization Forming 9,9’-Bifluorenylidene, Andrew Jourdan Eckelmann

MSU Graduate Theses

The ambition of this work is to start a path to the a priori rational design of high yield production for electron acceptors with finely tuned band gaps, from the comfort of an armchair. To this end, organic photovoltaics offer a cheap and sustainable means of manufacture using readily available materials and avoids the toxicity of some of the heavy metals used in first and second-generation solar cells such as cadmium. The microwave assisted Lawesson’s reagent mediated one-pot one-step solventless synthesis takes less than 3 minutes and results in an 84% yield of 9,9’-bifluorenylidene from two equivalents of fluorenone. While …

Errata For Manuscript #34, Carl W. David, Jan Siroky

Chemistry Education Materials

An error in manuscript 34 of this collection concerning the Laplacian in spherical polar coordinates is corrected.

Preparation Of Ni(Dpim)2Cl2 Complex For The Electrocatalytic Reduction Of Co2, Li-Pu Zhang, Dong-Fang Niu, Xin-Sheng Zhang

Journal of Electrochemistry

A new Ni(dpim)₂Cl₂complex using 2-(diphenylphosphino)-1-methylimidazole (dpim) as ligand was prepared and served as a catalyst for the electrochemical reduction of CO₂. The electrochemical redox behavior of Ni(dpim)₂Cl₂ in CH₃CN/TPABF₄ solution under nitrogen atmosphere showed the two-electron irreversible reduction at -0.7 V and one-electron quasi-reversible reduction at -1.3 V. After bubbling CO₂ into the electrolyte, the reduction peak appeared at -1.3 V became irreversible and the peak current increased from 0.48 mA·cm^-2 to 0.55 mA·cm^-2. Moreover, the peak current at -1.3 V could further increase …

Interaction Between Energy And Electrocatalysis—A Review On The 1st Young Scientist Forum On Energy Electrocatalysis, Hong Li, Wen-Bin Cai

Journal of Electrochemistry

No abstract provided.

Electrochemical Oxidation Of P-Chlorophenol On Porous Ti/Bdd Electrode Cooperated With Cathode Dechlorination, Rong-Ling Chen, Wei-Min Huang, Ya-Peng He, Jun Shi, Hai-Bo Lin

Journal of Electrochemistry

The electrochemical oxidation of p-chlorophenol on porous Ti/BDD electrode cooperated with synergistic effect of cathode dechlorination was studied. Electrochemical degradation tests of p-chlorophenol were conducted in single and double compartment electrolytic cells separately, and the results showed that the mineralization happened mainly in the anode region. The product of chloride ions produced from the cathodic reduction of 4-chlorophenol in the single cell migrated to the anode region and further generated active chlorine toward electro-catalytic oxidation. At the same time, the chloride ion produced from the cathode of the double cell was difficult to be migrated to the anode …

Preparation Of Co3O4/Ti Electrocatalytic Membrane Electrode For Catalytic Oxidation Of Benzyl Alcohol, Yu-Mei Zheng, Zhen Yin, Hong Wang, Jian-Xin Li

Journal of Electrochemistry

The cobalt oxide(Co₃O₄) nanoparticles were loaded on microporous Ti membrane to prepare Co₃O₄/Ti electrocatalytic membrane electrode by dip-coating method. The microstructures and electrochemical properties of Co₃O₄/Ti electrocatalytic membrane were investigated. The Co₃O₄/Ti electrocatalytic membrane reactor (ECMR) assembled by using the Co₃O₄/Ti electrocatalytic membrane as an anode was adopted for catalytic oxidation of benzyl alcohol to produce benzaldehyde and benzoic acid.The effects of different operation parameters on benzyl alcohol conversion, and selectivity to benzaldehyde and benzoic acid of ECMR were studied. …

A Label-Free Immunosensor Based On K3[Fe(Cn)6] And Aldehyde-Functionalized Pyridinium, Xia Hu, You-Ming Shen, Guang-Yu Shen

Journal of Electrochemistry

A novel aldehyde-functionalized pyridinium was successfully synthesized. Using K₃[Fe(CN)₆] as a redox species modified on the surface of the electrode through Poly(diallyldimethylammonium chloride), we developed a label-free immunosensor based on aldehyde-functionalized pyridinium that was applied to simplify antibody immobilization on the electrode surface, in which no additional chemical cross-linking was required. In addition, the introduction of K₃[Fe(CN)₆] on the surface of electrode avoided the use of other redox species in the electrolyte solution. Under the optimal experimental conditions, differential pulse voltammetry (DPV) signals corresponding to different α-Fetoprotein (AFP) concentrations were measured. …

Effects Of Rotating Magnetic Fields On Pem Fuel Cell Performance, Mao-Liang Wu, En-Ze Wang, Guang-De Pan, Zhong-Jun Liu, Fei Xie

Journal of Electrochemistry

Proton Exchange Membrane (PEM) fuel cell performance may be improved by application of additional magnetic fields. In this work, one square permanent magnet, made of either 16 combination cylinder magnets with homopolarity or 16 combination cylinder magnets with heteropolarity, was exerted on the fuel cell surface to produce additional magnetic field affecting PEM fuel cell performance. The influences of magnetic field status (rotating, static and none) on polarization and power density curves measured in a PEM fuel cell were investigated. The results verified the benefit of magnetic field, proving that the magnetic field distribution could improve the fuel cell output. …

Preparation And Properties Of Manganese Oxide And Polyaniline-Carbon Composite Electrode, Tian-Tian Zhou, Bing Wu, Chao Deng, Ying Gao

Journal of Electrochemistry

The polyaniline-carbon (PAnC) electrode was prepared by the polymerization of aniline monomer and activated carbon in ice water bath, and followed by chemical deposition of manganese dioxide MnO₂-PAnC composite material. The specific capacitance of MnO₂-PAnC reached 459 F•g^-1. The cyclic voltammetric results showed a small deformation in the voltammogram curve obtained with the MnO₂-PAnC electrode at high scan rate, indicating good reversibility and capacitive properties. The AC impedance results revealed that the MnO₂-PAnC electrode displayed the smallest charge transfer resistance and the fastest diffusion
rate of surface ions than other …

Electrochemical Performance Of Moo2-C Composite Coatings, Quan-Yi Li, Qi Yang, Yan-Hong Zhao

Journal of Electrochemistry

The molybdenum dioxide-carbon(MoO₂-C)composite coatings on the surface of Cu foils were prepared by simple knife coating route and followed by sintering in vacuum. The morphology, composition, structure and electrochemical performance of the MoO₂-C composite coatings were investigated. The results demonstrated that the MoO₂-C composite coatings consist of MoO₂ nano-particles with monoclinic crystal structure and amorphous carbon. Some MoO₂ nano-particles with a size range of 5-30nm were loaded on the surface of carbon matrices; while some MoO₂ nano-particles with a size of ~5nm were encapsulated inside. The composite coatings showed porous structure …

Preparations And Corrosion Protection Investigations Of Diethylene Triamine Penta(Methylene Phosphonic Acid)-Zn2+ Conversion Coatings On Cold Rolled Steel Substrates, Wei He, Ru Yan, Ying-Qi Wang, Xiang Gao, Hou-Yi Ma

Journal of Electrochemistry

Novel diethylene triamine penta(methylene phosphonic acid) (DTPMPA)-zinc ion (Zn²⁺) conversion coatings with uniform blue color and excellent corrosion protection were directly formed on the cold rolled steel (CRS) substrates by immersing a CRS plate into the film-forming solutions containing the appropriate concentrations of DTPMPA and Zn²⁺ ion at the proper pH. In this paper, surface morphologies and elemental compositions of DTPMPA-Zn²⁺ conversion coatings were characterized by SEM and EDS, respectivey. The surface functional groups, chemical constituents and binding modes to the substrates were investigated by means of FTIR and XPS methods. The influences of DTPMPA concentrations …

One-Step Co-Deposition Of Zsm-5/Pani/Pss Electroactive Film And Its Kinetics Characteristics Of Electrochemical Control Selective Separation For Pb2+ Ions, Wen-Lei Qiao, Xiao Du, Feng-Feng Gao, Jun-Lan Zheng, Sha-Sha Li, Xiao-Gang Hao

Journal of Electrochemistry

A novel electroactive composite film consisting of ZSM-5/polyaniline/polystyrene sulfonate(ZSM-5/PANI/PSS) was prepared by double pulse one step co-deposition method. The ZSM-5/PANI/PSS composite film was characterized by FT-IR, SEM, XRD, and XPS techniques. The highly crystalline nano-ZSM-5 was synthesized by hydrothermal method, which could be evenly dispersed in aqueous solution by ultrasonic treatment. The synthesis condition of composite film was optimized through changing the pH value of solution. The ZSM-5/PANI/PSS composite film showed higher adsorption capacity for Pb²⁺ ions. Langmuir model was applied to analyze the adsorption process. The adsorption capacity of composite film for Pb²⁺ ions was 235 mg·g …

Simulation Analysis In Dynamic Performance Of Proton Exchange Membrane Fuel Cell Under Starting Condition, Yan Xiao, Ying-Jie Chang, Wei Zhang, Qiu-Hong Jia

Journal of Electrochemistry

Based on the equivalent circuit model, by considering both the dynamic gas pressure model and the dynamic heat transfer model, a lumped parameter model is developed. The start process of the fuel cell is simulated by using SIMULINK software. The undershoot of the voltage is observed from the simulation results, and the response time of the voltage is basically the same as that of the fuel cell temperature, which indicates that the temperature has great influence on the dynamic performance of the fuel cell. From the perspective of the temperature, the dynamic responses of the thermodynamic potential, the activation overvoltage, …

Synthesis And Electrochemical Properties Of Li3V2(Bo3)3/C Anode Materials For Lithium-Ion Batteries, You Wang, Yi-Wen Zeng, Xing Zhong, Xing Liu, Quan Tang

Journal of Electrochemistry

The Li₃V₂(BO₃)₃/C (LVB/C) composite materials were successfully synthesized in two steps：Firstly, a stoichiomertric mixture of Li₂C₂O₄, V₂O₅, H₃BO₃, H₂C₂O₄•H₂O and ethanol was thoroughly ball-milled to get the precursors. Secondly, the precursors were post-calcinated to get the ultimate products. The calcination temperatures of 750 ℃, 800 ℃ and 850 ℃ were selected based on TG-DTA analyses. The crystal structures, surface morphologies and carbon contents of the samples calcinated at five conditions, …

Numerical Simulation Of Output Performance In Pemfc, Xin Luo, Shi-Zhong Chen, Yu-Hou Wu

Journal of Electrochemistry

The COMSOL software was used to analyze the output performances in proton exchange membrane fuel cell(PEMFC) under three kinds of flow fields. Under the same operating conditions, the performance differences among single serpentine flow field, interdigitated flow field and mixed flow field are compared, and the causes of the differences in the output performances of PEMFC under three kinds of flow fields were analyzed. The simulation results showed that the output performance of the mixed flow field was the best, the output performance of the interdigitated flow field the second and the output performance of single serpentine flow field the …

Computational And Analytical Modelling Of Droplet-Macroion Interactions, Myong In Oh

Electronic Thesis and Dissertation Repository

Charged droplets involving macromolecules undergo distinct disintegration mechanisms and shape deformations as a consequence of droplet-macroion interactions. Three general classes of droplet-macroion interactions that have been identified in the Consta group are: contiguous extrusion of a linear macroion from a droplet, "pearl-necklace" droplet conformations, and "star"-shaped droplets. This dissertation probes in a systematic manner the onset and various outcomes of macroion-droplet interactions, using atomistic molecular dynamics and realistic examples of solvent and macromolecules.

When the charge-squared-to-volume ratio of a droplet is below but near a threshold value, certain flexible macromolecules, such as poly(ethylene glycol), extrude from a droplet, induced by …