Physical Chemistry Commons^™

Preparations And Characterizations Of Ti/Pbo2 Electrodes Modified With Rare Earth Of Praseodymium And Pvp In Electrochemical Degradation Of Organics, Mai Xu, Feng-Wu Wang, Xian Liang, Yi-Jun Wei, Wen-Yan Fang, Chuan-Gao Zhu, Yun-Hu Hun

Journal of Electrochemistry

The titanium (Ti) based lead oxide (PbO₂) electrodes doped with praseodymium oxide (Pr₂O₃) and polyvinylpyrrolidone (PVP) were prepared by electrodeposition. The surface morphologies and structures of the as-prepared thin films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique, respectively. The results showed that the denser and more uniform coatings with smaller particles and larger surfaces were obtained by doping, which modified the micro-structure of the Ti/SnO₂-Sb₂O₃/Pr₂O₃-PVP-PbO₂ electrode. Cyclic voltammetry (CV) was also used to study the electrocatalytic activity of …

Electrocatalysis Of Nanotin Dioxide In The Battery Reaction Of Zinc-Nitrobenzene, Xu-Guo Tu, Xiang-Yu Ma, Rui-Nan He, Xiao-Juan Wang, Chen Ling, Yun-Xia Sun, Song Chen

Journal of Electrochemistry

The tin dioxide (SnO₂) nanoparticles were synthesized by using a simple hydrothermal route in the presence of tetrapropyl ammonium bromide (TPAB) as a surfactant. Accordingly, the titanium mesh based SnO₂ catalyst electrode was prepared. The morphologies and structures of SnO₂ nanostructures were characterized by scanning electron microscopy and X-ray diffraction spectrometry. The influences of reactant concentration, reaction temperature and time on the morphology of the products were investigated in detail. The electrocatalytic performance of SnO₂ for the reduction of nitrobenzene with zinc was studied. Possible formation process and growth mechanism for such hierarchical SnO_{2 …}

Selective Direct Electro-Oxidation Of C-H Bond, Yan-Mei Liao, Qian-Qian Wu, An-Lun Zhang, Ying-Hong Zhu, Chun-An Ma

Journal of Electrochemistry

Carbon-hydrogen (C-H) bond is the most basic chemical bond in organic compounds. The activation and direct conversion of C-H bond are the effective methodology for synthesis of different kinds of organic compounds from alkane compounds. The oxidative activation and functionalization of C-H bonds constitute an important and challenging area of investigation. The electro-oxidative activation of C-H bonds to form new C-O, C-C and C-N bonds has proven to be interesting and important in organic chemistry using the clean electron as the oxidant. The target C-O, C-C and C-N compounds could be selectively achieved by choosing the appropriate electrode, supporting electrolyte …

Wastewater Treatment Process Based On Microbial Electrochemistry: Opportunities And Challenges, Wei-Hua He, Jia Liu, Hai-Man Wang, Yu-Jie Feng

Journal of Electrochemistry

Microbial electrochemical technology (MET) has drawn great attention for its characteristics of synergetic pollution removal and energy recovery of wastewater. In the last decade, significant developments in microbial electrochemical system (MES) have been made in the aspects of electron transfer mechanism, microbial community analysis, function expansion, low-cost electrode materials and scaled-up constructions. However, the feasibility of MET as a wastewater treatment process has been controversial so far. In this paper, the characteristics of MET were systematically compared with anaerobic and aerobic processes from the application point of view in the aspects of pollution degradation and energy recovery processes. The MET-based …

Cathodic Electrochemiluminescence Of Meso-Tetra(4-Sulfophenyl)Porphyrin/Potassium Peroxydisulfate System, Yan-Fenga Wang, Dia Luo, Duo-Liang Shan, Xiao-Quan Lu

Journal of Electrochemistry

A new electrochemiluminescence (ECL) system in aqueous solution was constructed by using meso-tetra(4-sulfophenyl)porphyrin (TSPP) as a luminophoreand potassium peroxydisulfate (K2S2O8) as a reductive–oxidative coreactant. Upon sweeping from 0 V to -1.5 V, two cathodic ECL peaks were found simultaneously. One appeared at -0.8 V, which is corresponding to the reduction of TSPP, another at -1.2 V, that is attributed to the reduction of K2S2O8. And methylene blue could quench the ECL of TSPP effectively. In accordance with the linearity between quenching efficiency and the concentration of methylene blue, a method to determine methylene blue was established. The ECL mechanism was …

Characteristics And Mechanism For The Simons Electrochemical Fluorination Of Methanesulfonyl Fluoride, Wen-Lin Xu, Bao-Tong Li, Da-Wei Wang, Ya-Qiong Wang

Journal of Electrochemistry

The characteristics and mechanism for the Simons electrochemical fluorination processes were investigated during the electrochemical fluorination of CH₃SO₂F to CF₃SO₂F. The results showed that the reaction mechanism for the electrochemical fluorination of organic compounds to organic fluorides was the same as that of chemical fluorination processes using fluorinating agents such as CoF₃. The electrochemical fluorination in anhydrous HF was a heterogeneous process, and nickel fluorides on the surface of the nickel anode played the role of a mediator in the Simons process to transfer oxidation potential from the anode to …

Ionic Liquid-Supported Tempo/Polymeric Ionic-Liquid/Carbon Black Ternary Composites: Preparations And Applications In Electrochemical Oxidation Of Alcohols, Xin Lin, Cao-Cao Sun, Zhi-Rong Liu, Cheng-Chu Zeng

Journal of Electrochemistry

To effectively recover redox catalyst and supporting electrolyte, a novel ternary composite consisting of ionic liquid-supported TEMPO, polymeric ionic-liquid and carbon black was prepared. The ionic-liquid supported redox catalyst TEMPO-IL-BF₄ was firstly synthesized from 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, and followed by the reaction of polydimethyldiallylammonium chloride (PDDA) and bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) to form poly[diallyldimethylammonium bis(trifluoromethanesulfonyl)imide] (PDDA(Tf₂N)). A combination of the above mentioned two synthesized materials and carbon black afforded to obtain the ternary composite, which was used as the recoverable supporting electrolyte and mediator for the electrochemical oxidation of alcohol. The results indicate that various alcohols could be oxidized …

Preparations And Applications Of Irsnox Electrode In Electrochemical Synthesis Of 2,5-Dichlorophenol, Xiang-Yu Ma, Xu-Guo Tu, Rui-Nan He, Ya Chen, Gui-Sheng Zhu, Shou-Yan Shao, Song Chen

Journal of Electrochemistry

The electrodes of titanium based iridium tin oxides (IrSnOx) have been prepared by traditional thermal decomposition method and further applied to the electrosynthsis of 2,5-dichlorophenol in order to explore a green and high efficient synthesis route. The results showed that the electrode surface existed apparent cracks, while the intermediate layer prepared with Sn:Sb=94:6 existed less cracks and longer life time. The main products of the electrolytic reaction were 2,5-dichlorophenol, p-chlorophenol, and 1,2,4-trichlorobenzene. The electrosynthsis yield of 2,5-dichlorophenol reached 57% and the selectivity of 2,5-dichlorophenol was as high as 93% by using the IrSnOx as an anode, which is obviously better …

Electrochemical Deposition Of Cr From Cr3+ In The Mixed Electrolyte Of [Bmim]Oac/H2O, Wei Luo, Dong-Fang Niu, Rong-Bin Du, Jun-Wei Wang, Zhu-Qing Wang, Heng Xu, Xin-Sheng Zhang

Journal of Electrochemistry

The electrochemical reduction of trivalent chromium ion (Cr³⁺) to Cr in 1-butyl-3-methylimidazolium acetate ([BMIM]OAc)-H₂O mixed electrolyte was investigated. The cyclic voltammograms showed that the electroreduction of Cr³⁺ in the mixed electrolyte occurred in a two-step process, namely, Cr³⁺ + e → Cr²⁺ and Cr²⁺ + 2e→ Cr⁰, controlled by the diffusion of Cr³⁺ to the electrode. The diffusion coefficient of Cr³⁺ was 1.2×10^-8 cm²/s at 40 ℃ obtained by Rendle-Sevcik equation. The chronoamperomograms of the Cr³⁺ electrodeposition confirmed the three-dimensional instantaneous nucleation mechanism of …

Study On The Electrochemical Redox Mechanism Of Emodin, Dan Li, Bao-Kang Jin

Journal of Electrochemistry

The electrochemical reduction of emodin (Q) has been investigated in acetonitrile by cyclic voltammetry (CV), IR spectroelectrochemistry cyclic voltabsorptometry (CVA) and derivative cyclic voltabsorptometry (DCVA) techniques. It was found that anion radical Q^•− interacted with neutral Q to form dimer Q₂^•− which was further reduced to Q₂²⁻ at more negative potentials. A two-step one-electron process involving electrochemical reductions of Q₂²⁻ to form Q₂³⁻ in the first step and Q₂⁴⁻ in the second step, corresponding to the two cathodic peaks of C₃ and C₄ in CV curves was …

Conformational Studies Of Gram-Negative Bacterial Quorum Sensing 3-Oxo N-Acyl Homoserine Lactone Molecules, Darren Crowe, Alan Nicholson, Adrienne Fleming, Ed Carey, Goar Sanchez-Sanz, Fintan Kelleher

Articles

In their ¹H NMR spectra in CDCl₃ 3-oxo-N-acyl homoserine lactones (OHLs) show significant downfield chemical shifts of the amide N-H proton when compared to the parent N-acyl homoserine lactones (AHLs). NMR spectroscopic and DFT calculation studies have shown that this is most likely due to the presence of a stabilising intramolecular H-bond from the N-H to the 3-oxo group. The ¹H NMR spectra also show evidence for the enol tautomers and that the amount of enol present for a range of OHLs is 4.1-4.5% in CDCl₃ and 6.5-7.2% in CD₃CN. In …

The Investigation And Characterization Of The Reaction Of 2-Methylfuran And 2-Methyl-3-Buten-2-Ol With O(3p) And The Photodissociation Of Xylyl Bromide Isomers, Yasmin Fathi

Master's Theses

This thesis has studied the oxidation behavior of different biofuels or additives, 2-methyl-3-buten-2-ol and 2-methylfuran, in combustion experiments at the Chemical Dynamics Beamline held at the Advanced Light Source of the Lawrence Berkley National Laboratory. The oxidation of these fuels were initiated through O(³P) and the combustion experiments were analyzed using a multiplexed chemical kinetics photoionization mass spectrometer with tunable synchrotron radiation. Products of the different reactions were identified using kinetic profiles and further characterized using the photoionization spectra. The amount of each species was calculated using branching fractions.

Additionally, the unimolecular dissociation of the xylyl bromide isomers …

Application Of Bottlebrush Block Copolymers As Photonic Crystals, Allegra L. Liberman-Martin, Crystal K. Chu, Robert H. Grubbs

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone. These polymers display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures. The ability to prepare brush polymers with precise structures has been enabled by advancements in controlled polymerization techniques. This Feature Article highlights the development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light. Fabrication of these materials relies on polymer self-assembly processes to achieve nanoscale ordering, which allows for the rapid preparation …

Universal Disorder In Organic Semiconductors Due To Fluctuations In Space Charge, Tzucheng Wu

Physics & Astronomy ETDs

This thesis concerns the study of charge transport in organic semiconductors. These materials are widely used as thin-film photoconductors in copiers and laser printers, and for their electroluminescent properties in organic light-emitting diodes. Much contemporary research is directed towards improving the efficiency of organic photovoltaic devices, which is limited to a large extent by the spatial and energetic disorder that hinders the charge mobility. One contribution to energetic disorder arises from the strong Coulomb interactions between injected charges with one another, but to date this has been largely ignored. We present a mean-field model for the effect of mutual interactions …

Adsorption And Wetting In Model Mesoporous Silicas And In Complex Metal Oxide Catalysts, Karthik Jayaraman

Seton Hall University Dissertations and Theses (ETDs)

The surface of most metal oxides is covered by hydroxyl groups which influence many surface phenomena such as adsorption and wetting, catalysis and surface reactions. Surface chemistry of silica is a subject of exhaustive studies owing to a wide variety of practical applications of silica. In Chapter 1, a brief review of classification, synthesis and characterization of silica is provided. The hydroxylation of silica surface i.e the number of hydroxyl (-OH) groups on the surface is of utmost importance for its practical applications. In Chapter 2, a brief introduction to surface hydration of silica is provided followed by the gas …

Graphene Nanoribbons And Their Polymeric Nanocomposites: Controlled Synthesis, Characterization And Applications, Nada M. Aljehany

Electronic Theses & Dissertations

Carbon based materials are very promising as electrode materials energy generation and storage devices. They have been used for fuel cells, supercapacitors and solar cells. Among the carbon-based materials, graphene is very attractive due to its unique properties such as high electrical conductivity, good mechanical flexibility, large theoretical surface area (2630 m²/g), and high thermal and chemical stability. These unique properties make them very suitable for energy storage applications particularly for supercapacitors. The performance of the graphene as energy storage material could be further improved by growing them in nanoribbon form by unzipping carbon nanotubes. In this thesis, …

Real Time Monitoring Of Photocatalysis: An Application And Expansion Of The Quartz Crystal Microbalance, Perrin Godbold

Senior Honors Projects, 2010-2019

There are many applications of photocatalytic chemistry, with hundreds of researchers investigating photocatalytic materials. Another method of investigation could aid these researchers and contribute significantly to this field. This study attempts to develop a new method of analysis by expanding the capabilities of the Quartz Crystal Microbalance (QCM) into the realm of photocatalysis. We coated QCM crystals with the stable and well-known photocatalyst, titanium dioxide, and utilized these coated crystals to begin to develop an analysis procedure for our modified instrument. Some indication of the QCM’s sensitivity was seen, but the UV irradiation elicited a frequency change independent of the …

Ion-Specific Ice Recrystallization Provides A Facile Approach For The Fabrication Of Porous Materials, Shuwang Wu, Chongqin Zhu, Zhiyuan He, Han Xue, Qingrui Fan, Yanlin Song, Joseph S. Francisco, Xiao Cheng Zeng, Jianjun Wang

Xiao Cheng Zeng Publications

Ice recrystallization is of great importance to both fundamental research and practical applications, however understanding and controlling ice recrystallization processes remains challenging. Here, we report the discovery of an ion-specific effect on ice recrystallization. By simply changing the initial type and concentration of ions in an aqueous solution, the size of ice grains after recrystallization can be tuned from 27.4±4.1 to 277.5±30.9 mm. Molecular dynamics simulations show that the ability of the ion to be incorporated into the ice phase plays a key role in the ultimate size of the ice grains after recrystallization. Moreover, by using recrystallized ice crystals …

Kinetic Study Of Conjugated Polymer Packing And Agglomeration, Skye R. Travis

Honors Theses

Although organic electronic materials are flexible, cheap to fabricate, and molecularly tunable, their performance has generally been less efficient than that of their inorganic counterparts. Chemical doping has been attempted as a method to increase the efficiency of organic materials. During this process, an organic material, typically a conjugated polymer, is exposed to an oxidant/reductant, called a dopant. Electron transfer between host polymer and dopant molecules increases the charge carrier density in the doped host material, making it a more efficient conductor. The effects of doping using 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4TCNQ) on low molecular weight poly(3-hexylthiophene-2,5-diyl) (LMW P3HT) in varying ratios of …

Homogeneous Ligand-Centered Hydrogen Evolution And Hydrogen Oxidation : Exploiting Redox Non-Innocence To Drive Catalysis., Andrew Z. Haddad

Electronic Theses and Dissertations

Hydrogen is a promising carbon-free fuel / energy carrier and is an essential building block for many industrial and agricultural processes. Rising energy demands have ignited interest in the development of carbon-free and carbon neutral energy sources. In this context, hydrogen is an attractive candidate—being energy-dense, carbon-free—and easily accessible through a two-electron reduction of water. Accordingly, many electrochemical homogeneous catalyst systems have been studied, with a focus on understanding the mechanism of hydrogen evolution proceeding through metal-hydride intermediates. However, there has been a renaissance in hydrogen evolution reaction (HER) catalyst design, with many groups implicating ligand redox non-innocence as a …

Ab Initio And Semi-Empirical Calculations Of Cyanoligated Rhodium Dimer Complexs, Yazeed Asiri

Electronic Theses and Dissertations

Molecular modeling, using both ab initio and semi-empirical methods has been undertaken for a series of dirhodium complexes in order to improve the understanding of the nature of the chemical bonding in this class of homogeneous catalysts. These complexes, with carboxylamidate and carboxylate ligands, are extremely functional metal catalysts used in the synthesis of pharmaceuticals and agrochemicals. The X-ray crystallography shows anomalies in the bond angles that have potential impact on understanding the catalysis. To resolve these issues, minimum energy structures of several examples (e.g. Rh₂(NHCOCH₃)₄, Rh₂(NHCOCH₃)₄NC, Rh …

In Situ Electron Microscopy Of Plasmon-Mediated Nanocrystal Synthesis, Peter Sutter, Ying Li, Christos Argyropoulos, Eli A. Sutter

Department of Electrical and Computer Engineering: Faculty Publications

Chemical processes driven by nonthermal energy (e.g., visible light) are attractive for future approaches to energy conversion, synthesis, photocatalysis, and so forth. The growth of anisotropic metal nanostructures mediated by excitation of a localized surface plasmon resonance (LSPR) is a prototype example of such a reaction. Important aspects, notably the growth mechanism and a possible role of plasmonic “hot spots” within the metal nanostructures, remain poorly understood. Here, we use in situ electron microscopy to stimulate and image the plasmon-mediated growth of triangular Ag nanoprisms in solution. The quantification of the time-dependent evolution of the lateral size and thickness of …

Morphology Controlled Synthesis Of Copper Based Multimetallic Nanostructures And Their Electrocatalytic Properties For Methanol Oxidation Reaction, Leanne Elizabeth Mathurin

Graduate Theses and Dissertations

This research focuses on the development of shape-controlled synthesis of Cu NM, Cu-based bimetallic and trimetallic nanostructures, and their electrocatalytic properties for methanol oxidation reaction (MOR). Copper nanomaterials (Cu NM) with specific surface facets can tailor their catalytic activity. Understanding reagents responsible for Cu NM growth is important for morphology-controlled synthesis of the nanostructures. This research studies the halide influence on Cu NM growth and morphology in an oil-based synthesis. The morphology of the Cu NM varies with the halide type (i.e., Cl-, Br-, I-), and the halide concentration. Additionally, the type of Cu precursor also influenced the morphology of …

Electrochemical Time Of Flight For Rapid And Direct Measurement Of Diffusion Coefficients, Jonathan C. Moldenhauer

Graduate Theses and Dissertations

The determination of diffusion coefficients is of fundamental importance to the understanding of electrochemistry and sensors. Developing a method by which diffusion coefficients of Red/ox active analytes can be determined quickly and elegantly, would be a great advancement over presently accepted methods. This dissertation reports the reviving electrochemical time of flight (ETOF), and developing a method that allows for empirical determination of diffusion coefficients from a single measurement. ETOF is a generate and detect experiment where the time an electrochemically generated species takes to transit a known distance is measured and related to the diffusion coefficient of the species. The …

Novel Composites Between Nano-Structured Nickel Sulfides And Three-Dimensional Graphene For High Performance Supercapacitors, Xiaomin Wang, Huanglin Dou, Zhen Tian, Jiujun Zhang

Journal of Electrochemistry

In this paper, a three-dimensional graphene (3DG) network grown on nickel foam was employed as a template for synthesizing graphene-based composite materials of supercapacitor electrode. The composites (crystal Ni₃S₂ nanorods on the surface of 3DG (abbreviated as Ni₃S₂/3DG)) were obtained through a one-step hydrothermal reaction. The morphological and structural evolution of the Ni₃S₂/3DG composites were investigated by SEM, TEM, XRD and Raman spectroscopy. Detailed electrochemical characterization showed that the Ni₃S₂/3DG-coated electrodes exhibited both a specific capacitance as high as 1825 F·g^-1 at 5 mV·s …

Rutile Tio2 Nanosheet Arrays Planted On Magnetron Sputtered Ti Metal Layers For Efficient Perovskite Solar Cells, Nang Zhang, Meidan Ye, Xiaoru Wen, Changjian Lin

Journal of Electrochemistry

In this work, vertical rutile titanium oxide (TiO₂) nanosheet arrays (NSAs) were firstly hydrothermally grown on the top of thin titanium (Ti) metal layers which were loaded on fluorine doped tin oxide (FTO) substrates by the DF magnetron sputtering deposition method. After an annealing post-treatment, the Ti metal layers were transformed into the compact TiO₂ layers with a strong connection between the rutile TiO₂ NSAs and the FTO substrates. For comparison, the rutile TiO₂ NSAs were similarly planted over two compact TiO₂ layers fabricated through atomic layer deposition (ALD) and spin coating (SC) methods, …

Preface: Special Issue In Honor Of Professor Zhaowu Tian On His 90Th Birthday, Shigang Sun, Changjian Lin, Bingwei Mao

Journal of Electrochemistry

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Designing Pt-Skin Of Pt-Based Bimetallic Electrocatalysts For Oxygen Reduction Reaction, Binwei Zhang, Yunxiao Wang, Yanfei Xu, Huakun Liu, Shixue Dou

Journal of Electrochemistry

In the past decade, great advancement has been made in the development of nanocatalysts for energy conversion and storage. Pt-skin of Pt-based bimetallic has shown a great potential in the tuning the electronic structures of electrocatalytically active materials toward oxygen reduction reaction. Here, we offer a brief overview of the recent research on the design and preparation of catalysts. Our focus is paid on the systematic studies of preparation and performance of Pt-skin catalysts towards oxygen reduction reaction.

Recent Progress In Template-Assisted Synthesis Of Nitrogen-Doped Porous Carbons For Oxygen Electroreduction, Wenhan Niu, Ligui Li, Shaowei Chen

Journal of Electrochemistry

Nitrogen (N)-doped porous carbons are potential alternatives to precious metal catalysts for oxygen reduction reaction (ORR) at the cathodes of proton exchange membrane fuel cells and metal-air batteries. Template-assisted synthesis has been used extensively as a robust and versatile method in the preparation of such carbon catalysts, where the ORR activity has been found to be dependent on various structural parameters, such as the concentrations and molecular configurations of the dopants, and the porosity, surface accessibility and electrical conductivity of the carbon materials. In this review, we summarize recent progress in this area of research focusing on the design, preparation …

Electrochemical Methods In Clinical Immunoassays And Nucleic Acid Analyses, Yanbing Zu

Journal of Electrochemistry

The applications of electrochemical methods in immunoassays and nucleic acid analyses are discussed. Instead of a comprehensive literature review, this paper focuses on the techniques that have already been commercialized and used in clinical diagnoses. Learning from the success of these methods will help us to further understand the strengths and limitations of electroanalytical technology. A personal perspective of the research and development in these fields has been presented.