Catalysis and Reaction Engineering Commons^™

Cobalt-Based Nitrogen-Doped Carbon Non-Noble Metal Catalysts For Oxygen Reduction Reaction, Meng-Xiu Jiang, Jing Zhang, Yue-Hua Li, Rong Zhang

Journal of Electrochemistry

Transition metal-nitrogen co-doped carbon catalysts have attracted significant attention because of their reasonable activity and remarkable selectivity toward oxygen reduction reaction (ORR) as cathodic reaction in fuel cells. However, the role of transition metal in the active sites of the catalysts still is uncertain. In this work, the Co_x-N_y/C-T catalysts were prepared with BP2000 as a carbon source, urea (Ur) as a nitrogen source and Co(OAc)₂•4H₂O as a metal precursor by a simple chemical method. Meanwhile, in order to optimize the ORR activity, the catalysts were synthesized with different amounts of Co …

Core-Shell Pd@Pt Ultrathin Nanowires As Durable Oxygen Reduction Electrocatalysts, Xin Wang, Yun-Jie Xiong, Liang-Liang Zou, Qing-Hong Huang, Zhi-Qing Zou, Hui Yang

Journal of Electrochemistry

This paper describes a simple CO-assisted reduction approach for the controllable synthesis of ultrathin Pd nanowires along the one-dimensional (1D) direction. Ultrathin Pt films from one to several atomic layers were successfully decorated onto ultrathin Pd nanowires by utilizing Cu UPD deposition, and followed by in-situ redox replacement reaction of UPD Cu by Pt. The core–shell structure and composition of the Pd@Pt ultrathin nanowires have been verified using transmission electron microscopy and energy dispersive X-ray spectrometry. The core–shell Pd@Pt ultrathin nanowires exhibited comparative electrocatalytic activity and improved durability for the oxygen reduction reaction in comparison with commercial Pt black. The …

Kinetics And Mechanism Toward Electrochemical Reductions Of Sodium Bromide And Methanol Over Iron Electrodes, Qun Liao, Shu-Feng Zhang, Wen-Hua Leng

Journal of Electrochemistry

It is of technological value and scientific interest to the electro-synthesis of ferrocene, conversion of carbon dioxide (CO₂) and organic electro-synthesis in non-aqueous solutions by investigating the kinetics and mechanism toward electrochemical reductions of sodium bromide (NaBr) and methanol over iron electrodes. However, few reports in the related researches are available. In this article, the kinetics and mechanism toward electrochemical reductions of NaBr and methanol over iron electrodes were examined in detail by carrying out the polarization curve and electrochemical impedance spectroscopic measurements. The results showed that methanol was the reactant, while Na⁺ ions were functioned only …

Electroactivities Of Pd/Fe3O4-C Catalysts For Electro-Oxidation Of Methanol, Ethanol And Propanol, Tao Zou, Qing-Feng Yi, Yuan-Yuan Zhang, Xiao-Ping Liu, Guo-Rong Xu, Hui-Dong Nie, Xiu-Lin Zhou

Journal of Electrochemistry

Development of palladium (Pd) catalysts with high electroactivity for alcohol oxidation is significant for alcohol fuel cells. In this work, Pd nanoparticles were formed by sodium borohydride (NaBH₄) reduction method and subsequently deposited on the surface of carbon supported ferriferrous oxide (Fe₃O₄/C) composites to obtain the Pd/Fe₃O₄-C catalysts with different Fe₃O₄ loadings. Their transmission electron microscopic (TEM) images show that the Pd nanoparticles were uniformly dispersed on the Fe₃O₄/C. Electroactivities of the prepared Pd/Fe₃O₄-C catalysts toward oxidations of C1-C3 …

Effect Of Fe2+/Fe3+Interconvertion On Reduction Behavior Of Fe3+ In Acidic Electrolytes, Jian-Xin Qin, Feng Lin, Wen-Ping Liu, Chao Chen, Meng-De Ren

Journal of Electrochemistry

The influences of ferrous/ferric (Fe²⁺/Fe³⁺) interconvertion on electrochemical reduction and electrode reaction of Fe³⁺ were investigated by using linear sweep voltammetry, potentiostatic method and cyclic voltammetry (CV) in acidic electrolytes containing chloride ion (Cl^- ) and sulfate ion (SO₄^2-). It was shown that the reduction process of Fe³⁺/Fe²⁺ would take place in two independent stages: (1) the reduction of Fe³⁺ to Fe²⁺ at E=0.35V and (2) the co-precipitation of Fe²⁺ by forming Fe(OH)₂ (E≤-0.3 V) instead of Fe. The major effect of Fe^{2+ …}

An Application Of M-Matrices To Preserve Bounded Positive Solutions To The Evolution Equations Of Biofilm Models, Richard S. Landry Jr.

University of New Orleans Theses and Dissertations

In this work, we design a linear, two step implicit finite difference method to approximate the solutions of a biological system that describes the interaction between a microbial colony and a surrounding substrate. Three separate models are analyzed, all of which can be described as systems of partial differential equations (PDE)s with nonlinear diffusion and reaction, where the biological colony grows and decays based on the substrate bioavailability. The systems under investigation are all complex models describing the dynamics of biological films. In view of the difficulties to calculate analytical solutions of the models, we design here a numerical technique …

Fabrication And Modification Of Titania Nanotube Arrays For Harvesting Solar Energy And Drug Delivery Applications, Ahmed El Ruby Abdel Rahman Mohamed

Electronic Thesis and Dissertation Repository

The fast diminishing of fossil fuels in the near future, as well as the global warming caused by increasing greenhouse gases have motivated the urgent quest to develop advanced materials as cost-effective photoanodes for solar light harvesting and many other photocatalytic applications. Recently, titania nanotube arrays (TNTAs) fabricated by anodization process has attracted great interest due to their excellent properties such as: high surface area, vertically oriented, highly organized, one-dimensional, nanotubular structure, photoactivity, chemical stability and biocompatibility. This unique combination of excellent properties makes TNTAs an excellent photoanode for solar light harvesting. However, the relatively wide band gap energy of …

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara

Physics and Astronomy Faculty Publications

The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts as a …

An Exploration Of Basic Processes For Aqueous Electrochemical Production Of Hydrogen From Biomass Derived Molecules, Brian Fane

Doctoral Dissertations

Polymer electrolyte membrane fuel cells(PEMFCs) are energy conversion devices with significant potential. The factors preventing them from becoming widespread concern production and distribution of hydrogen. Developing an efficient hydrogen infrastructure with an approachable rollout plan is an essential step towards the future of fuel cells. Water electrolysis is limited by the thermodynamics of the process, which leads to high electrical consumption and significant materials challenges. Alternative methods for cleanly generating hydrogen while using a lower cell voltage are required. PEM based electrolyzers can operate with a "depolarized anode", whereby they become significantly less power hungry.

This thesis explores two techniques …

Multiscale Modeling Approach To Understand Active Sites In Non-Conventional Catalyst Layers For Fuel Cell Applications, Diana Constanza Orozco Gallo

Doctoral Dissertations

Fuel cells development required stable, active and more abundant catalytic materials. Oxygen reduction reaction (ORR) is the key process to enhance better activity and reduce the fabrication costs. Pt-based has proven to be the best catalyst for ORR and greater efforts has been made in terms of reducing the Pt content in the electrodes, reduce electrode thickness and enhance better catalytic activities. To overcome many of the challenges present, the catalyst layer studies are the great importance in the fuel cell community. Understanding catalyst layer with new catalytic materials, and configurations requires the development of methodological approach to relate structure, …

Computational Studies Of Structure–Function Relationships Of Supported And Unsupported Metal Nanoclusters, Hongbo Shi

Doctoral Dissertations

Fuel cells have been demonstrated to be promising power generation devices to address the current global energy and environmental challenges. One of the many barriers to commercialization is the cost of precious catalysts needed to achieve sufficient power output. Platinum-based materials play an important role as electrocatalysts in energy conversion technologies. In order to improve catalytic efficiency and facilitate rational design and development of new catalysts, structure–function relationships that underpin catalytic activity must be understood at a fundamental level. First, we present a systematic analysis of CO adsorption on Pt nanoclusters in the 0.2-1.5 nm size range with the aim …

Analyses Of Densely Crosslinked Phenolic Systems Using Low Field Nmr, Jigneshkumar Patel

Doctoral Dissertations

A uniform dispersion of reactants is necessary to achieve a complete reaction involving multi-components, especially for the crosslinking of rigid high-performance materials. In these reactions, miscibility is crucial for curing efficiency. This miscibility is typically enhanced by adding a third component, a plasticizer. For the reaction of the highly crystalline crosslinking agent hexamethylenetetramine (HMTA) with a strongly hydrogen-bonded phenol formaldehyde resin, furfural has been traditionally used as the plasticizer. However, the reason for its effectiveness is not clear. In this doctoral thesis work, miscibility and crosslinking efficiency of plasticizers in phenolic curing reactions are studied by thermal analysis and spectroscopic …

Thermo-Stability And Active Site Structure Of Fe/N/C Electrocatalyst For Oxygen Reduction Reaction, Chi Chen, Yu-Jiao Lai, Zhi-You Zhou, Xin-Sheng Zhang, Shi-Gang Sun

Journal of Electrochemistry

The development of Fe/N/C electrocatalyst for oxygen reduction reaction (ORR) is vital for the large-scale applications of proton exchange membrane fuel cells. Understanding the active site structure will contribute to the rational design of highly active catalysts. In this study, the as-prepared Fe/N/C catalyst based on poly-m-phenylenediamine (PmPDA-FeN_x/C) catalyst with the high ORR activity was subjected to the high-temperature heat treatment again at 1000 ~1500 ^oC. The degradation of in the ORR activity of PmPDA-FeN_x/C by with various heat treatments was correlated to the change of elemental compositions, chemical states and textural properties. As the …

A New Type Carbon Composited Molybdenum Doped Vanadium Oxide Nanowires As A Cathode Material For Sodium Ion Batteries, Guang-Rui Zhang, Li-Qiang Hu, Bao-Zhu Zhang

Journal of Electrochemistry

In recent years, the development of lithium ion batteries (LIBs) has been limited due to the insufficient lithium resource and increasing cost. As a promising candidate, sodium ion batteries (SIBs) with the similar electrochemical mechanism and lower cost than LIBs are developing rapidly. However, as a result of the larger radius of Na⁺ compared with Li⁺, the crystalline structures of the most electrode materials are damaged severely during the intercalation of Na⁺, which limits the electrochemical properties of SIBs. Thus, developing new types of electrode materials for SIBs is particularly important. Among the cathode materials, …

Creating Renewable Tunable Polymers From Hydroxymethylfurfural, Meredith C. Allen

Electronic Theses and Dissertations

The research here deals with the conversion of 5-hydroxymethylfurfural (HMF) into a tunable polymer. HMF is a known derivative that can be acquired from biomass via hydrolysis of cellulose followed by isomerization and finally selective dehydration. The process considered here is being developed to create tunable polymers from HMF and involves several different steps, three of which are covered here. The first step, an etherification, is the reaction of HMF with an alcohol. This step is significant because in this step the R-group from the alcohol is added to HMF and the branching portion formed is carried over to the …

Catalytic Oxidation And Depolymerization Of Lignin In Aqueous Ionic Liquid, Lalitendu Das, Siquan Xu, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Lignin is an integral part of the plant cell wall, which provides rigidity to plants, also contributes to the recalcitrance of the lignocellulosic biomass to biochemical and biological deconstruction. Lignin is a promising renewable feedstock for aromatic chemicals; however, an efficient and economic lignin depolymerization method needs to be developed to enable the conversion. In this study, we investigated the depolymerization of alkaline lignin in aqueous 1-ethyl-3-methylimidazolium acetate [C₂C₁Im][OAc] under oxidizing conditions. Seven different transition metal catalysts were screened in presence of H₂O₂ as oxidizing agent in a batch reactor. CoCl₂ and …

Enhancements In Mass Transfer For Carbon Capture Solvents Part I: Homogeneous Catalyst, Leland R. Widger, Moushumi Sarma, Jonathan J. Bryant, David S. Mannel, Jesse G. Thompson, Cameron A. Lippert, Kunlei Liu

Center for Applied Energy Research Faculty and Staff Publications

The novel small molecule carbonic anhydrase (CA) mimic [Co^III(Salphen-COO⁻)Cl]HNEt₃ (1), was synthesized as an additive for increasing CO₂ absorption rates in amine-based post-combustion carbon capture processes (CCS), and its efficacy was verified. 1 was designed for use in a kinetically slow but thermally stable blended solvent, containing the primary amines 1-amino-2-propanol (A2P) and 2-amino-2-methyl-1-propanol (AMP). Together, the A2P/AMP solvent and 1 reduce the overall energy penalty associated with CO₂ capture from coal-derived flue gas, relative to the baseline solvent MEA. 1 is also effective at increasing absorption kinetics of kinetically fast solvents, such …

Ion Size Effects On The Properties Of Charge Regulating Electric Double Layers, Divya Jyoti Prakash

Nanoscience and Microsystems ETDs

The behavior of charged interfaces formed in various systems like colloidal solution, fuel cells, battery, electro-deposition, catalysis is governed by the properties of electrical double layer(EDL). Civilized model with charge regulation boundary condition determined by thermodynamic equilibrium at the interface has been used to model electrical double layer and shows that size of the solvent plays a critical role in characterizing the properties of EDL using classical density functional theory.This thesis investigates the impact of ion size in electrolyte solutions on the electrical double layer formed at the interface using a similar model. It is found that ion size greatly …

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 …

Electrochemical Synthesis Of Homoallylic Alcohols And Homoallylic Amines, Wei-Qiang Zhong, Xiang-Hui Liang, Jing-Mei Huang

Journal of Electrochemistry

Electrochemical technique has been widely applied in the organic synthesis. This review focuses on the electrochemical synthesis of homoallylic alcohols and homoallylic amines from the allylation of carbonyl compounds and imines. This method has been developed impressively, especially in the field of electrochemical allylation in a green solvent of aqueous media. Improvement of the efficiency of the electricity, regio-selectivity and chiral synthesis are expected.

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 …

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 …}

Comparison Of Oxygen Reduction Reaction Activity Of Pt-Alloy Nanocubes, Yongan Tang, Lin Dai, Shouzhong Zou

Journal of Electrochemistry

Alloying Pt with the first row non-noble transition metals has been demonstrated to increase the catalytic activity toward oxygen reduction reaction (ORR), which is the cathode reaction of the proton exchange membrane fuel cells (PEMFCs) and metal-air batteries. However, how much the ORR activity improvement comes from the alloying elements remains controversial. In this paper, the nanocubes of PtMn, PtFe, PtCo, and PtNi with the similar size and composition were prepared and their ORR activities were explored, in order to investigate the effects of alloying elements on the catalytic activity. The use of cubic shape particles minimizes the contribution to …

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.

Comparative Studies Of Fe, Ni, Co And Their Bimetallic Nanoparticles For Electrochemical Water Oxidation, Maduraiveeran Govindhan, Brennan Mao, Aicheng Chen

Journal of Electrochemistry

The design of efficient, durable, and earth-abundant electrocatalysts via environmentally compatible strategies for the oxygen evolution reaction (OER) is a vital for energy conversion processes. Herein we report a facile approach for the fabrication of low-cost and earth abundant metal catalysts, including iron (Fe), nickel (Ni), cobalt (Co), CoNi, and CoFe nanoparticles (NPs) on titanium (Ti) substrates through a one-step electrochemical deposition. Field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) spectrocopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques were employed to characterize these nanoparticles. Our electrochemical results revealed that among the five synthesized nanomaterials, the …

Impact Of Nafion Loading And Anion Adsorption On The Synthesis Of Pt Monolayer Core-Shell Catalysts, Lijun Yang, Dustin Banham, Elod Gyenge, Siyu Ye

Journal of Electrochemistry

Carbon supported palladium (Pd) nanoparticles were used as a model core material for the synthesis of platinum (Pt) monolayer core-shell catalysts using rotating disk electrode method and a copper (Cu) under potential deposition technique. The impact of Nafion on the synthesis process was revealed by electrochemical testing with various Nafion contents. The existence of Nafion influenced the Cu under potential deposition, galvanic replacement and eventually the oxygen reduction reaction activity of the core-shell catalyst. However, as long as the Nafion content was less than 5 wt% in the test film, adding Nafion could help to bind catalyst onto the surface …

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

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 …

Electrodeposition Of Ruo2 Layers On Tio2 Nanotube Array Toward Co2 Electroreduction, Bei Jiang, Lina Zhang, Xianxian Qin, Wenbin Cai

Journal of Electrochemistry

RuO₂/TiO₂ composite materials have multitude of electrocatalytic applications including but not limited to CO₂ reduction reaction (CO₂RR). RuO₂/TiO₂ electrodes were previously prepared by repetitive coating and thermal decomposition (TD) of a Ru(III) precursor solution on Ti substrate. In this work, electrochemical potential cycling is applied to deposit amorphous RuO₂ (α-RuO₂) layers onto TiO₂ nanotube array (TNA) (RuO₂^CV/TNA) preformed on Ti foil. SEM, GIXRD, and voltammetry are applied to characterize the structures of the resulting Ru_O2^CV/TNA. Ru loading on the RuO_{2 …}