Engineering Commons^™

Stm Investigation Of Oxygen Reduction Reaction On Solid Interface In Fuel Cell, Zhen-Feng Cai, Bing Sun, Wen-Jie Jiang, Ting Chen, Dong Wang, Li-Jun Wan

Journal of Electrochemistry

An electrocatalyst for oxygen reduction reaction (ORR) is an important component for fuel cells. An investigation at interfacial electrochemical reactions toward ORR at a molecular scale benefits mechanistic understanding as well as rational design of catalysts. Scanning tunneling microscopy (STM) has been proven to be a powerful tool to monitor chemical reactions and to provide in-situ information about the interfacial electrochemical reactions at a molecular level. This review summarizes the recent STM studies in monitoring the interface processes such as morphological changes, molecular changes, reaction intermediates, and oxidation products. The prospects of future development in this field are outlined.

A Study On The Oxidation Of Hydrogen Peroxide At Au(111) And Au(100) Electrodes, Yong-Li Zheng, Jie Wei, Yan-Xia Chen

Journal of Electrochemistry

The oxidation reactions of hydrogen peroxide (H₂O₂) at Au(111) and Au(100) electrodes in 0.1 mol·L^-1 HClO₄ were investigated by using rotating disk electrode system. It was found that H₂O₂ could be readily oxidized to O₂ at both Au(100) and Au(111) surfaces with the onset potential close to its equilibrium potential. In contrast, the onset overpotential for H₂O₂ reduction was above 0.4 V, while the onset overpotential for H₂O₂ oxidation at Au(100) was ca. 0.1 V more negative than that at Au(111), this is probably …

Syntheses Of Ag@Pd@Pt Nanoparticles With Tunable Shell Thickness For Electrochemical Oxidation Of Formic Acid, Xiao-Dong Lin, Du-Hong Chen, Zhong-Qun Tian

Journal of Electrochemistry

In an effort to lower cost of a catalyst, the silver (Ag) core with palladium (Pd) layer then platinum (Pt) island (Ag@Pd@Pt) nanoparticles were synthesized and the electrocatalytic activity of Ag@Pd@Pt nanoparticles on formic acid was compared with that of Au@Pd@Pt nanoparticles reported previously. The results showed that the existence of a small amount of Pt could significantly improve the activity of the catalyst. When the surface coverage of Pt approached 0.5 monolayers, the activity of Ag@Pd@Pt nanoparticles reached the maximum. Though the onset potential of the electro-oxidation was slightly more positive (about 50 mV), the overall electrocatalytic activity of …

Chitosan/Nonahydrate Gel Derived Fe-N-Doped Porous Carbon Sheet As High-Efficient Orr Electrocatalyst, Fan-Lu Meng, Xin-Bo Zhang, Jun-Min Yan

Journal of Electrochemistry

The chitosan/nonahydrate gel was used as a precursor to realize the uniform mixture of N-polymer and metal salt. After lyophilization treatment, the gel went through heat treatment and acid etch. Accordingly, the Fe-N-doped porous carbon sheet with homogenous composition and microstructure was prepared. Compared with the commercial Pt/C catalyst, the Fe-N-doped porous carbon sheet exhibited more positive onset potential and half-wave potential, higher current density, and especially, excellent durability. The power density of 318 mW·cm^-2 was obtained in alkaline fuel cell with the Fe-N-doped porous carbon sheet as a cathode catalyst, which is higher than 267 mW·cm^-2 with …

Synthesis Of Ultrathin Co3O4 Nanoflakes Film Material For Electrochemical Sensing, Hui-Juan Wang

Journal of Electrochemistry

Ultrathin cobalt oxide (Co₃O₄ ) nanoflakes film material was synthesized by using an electro-deposited cobalt layer as a raw material through a simple oxidation method and followed by a heat treatment at 350 ^oC. The physical characterizations of the Co₃O₄ nanoflakes film were performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) technologies, and the electrochemical activity was measured by cyclic voltammetry (CV). As a promising material for electrochemical sensing, the as-synthesized ultrathin Co₃O₄ nanoflakes film material exhibited excellent electrochemical activity for H₂O …

Impedance-Resolved Performance And Durability In Redox Flow Batteries, Alan Michael Pezeshki

Doctoral Dissertations

The realization of redox flow batteries (RFBs) as a grid-scale energy solution depends on improving the performance and lifetime of the technology to decrease the high capital costs. The electrodes are a key component in the RFB; performance enhancement is often achieved through chemical or thermal treatments of commercially available porous carbon materials.

This dissertation uses impedance spectroscopy-based methods to gain insight into performance and durability in RFBs, enabling intelligent cell design. Initial work focused on understanding the impact of improved electrode and membrane properties on system performance. An accelerated stress test was then developed that can be used to …

Characterization Of Molecular Communication Based On Cell Metabolism Through Mutual Information And Flux Balance Analysis, Zahmeeth Sayed Sakkaff

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

Synthetic biology is providing novel tools to engineer cells and access the basis of their molecular information processing, including their communication channels based on chemical reactions and molecule exchange. Molecular communication is a discipline in communication engineering that studies these types of communications and ways to exploit them for novel purposes, such as the development of ubiquitous and heterogeneous communication networks to interconnect biological cells with nano and biotechnology-enabled devices, i.e., the Internet of Bio-Nano Things. One major problem in realizing these goals stands in the development of reliable techniques to control the engineered cells and their behavior from the …

Innovative Electrode Nanocomposites For Energy Storage And Conversion Systems, Yiran Wang

Doctoral Dissertations

Nanocomposites emerged as suitable alternatives for electrode materials, are defined as “two or more materials with different properties remain separate and distinct on a macroscopic level within one unity and with any dimension in any phase less than 100 nm”. Recently, polymer/carbon based nanocomposites have attracted significant research interests for energy applications due to their multi-functionalities, improved structure stability and ease of production. This dissertation work focusing on the development of innovative electrode nanocomposites for proton exchange membrane fuel cell, supercapacitor and electrochromic applications.

Chapter 1 is an introduction. Chapter 2 & 3 focus on the synthesis of Pd-based nanocatalysts …

Effects Of Ultrasonic Transducers On Heat Transfer In Packed Particle Beds, David Patrick Moseley

Masters Theses

The objective of this study was to determine the effects of ultrasonic transducers on heat transfer in a packed particle bed heat exchanger. Although substantial research has been devoted to ultrasound, and the associated improvements in heat transfer, data regarding the effects on packed particle beds is non-existent. This is of particular interest given the potential to improve heat transfer in a wide variety of packed particle bed systems. A 42.9% increase in the heat transfer rate was demonstrated as the result of improved fluid convection throughout the packed particle bed. Secondary effects, including acoustic cavitation, acoustic streaming and local …

Lignin Maximization: Analyzing The Impact Of Different Feedstocks And Feedstock Ratios Using Organosolv Fractionation, Marc Banholzer

Masters Theses

Over-exploitation of fossil fuels coupled with increasing pressure to reduce carbon emissions are prompting a transition from conventional petrochemical feedstocks to sustainable and renewable sourced carbon. The use of lignocellulosic biomass as a feedstock for integrated biorefining is of current high interest, as separation into its component parts affords process streams of cellulose, hemicellulose and lignin, each of which can serve as a starting point for the production of biobased chemicals and fuels. Given the large number of potential sources of lignocellulosic feedstocks, the biorefinery will need to adapt to the supplies available over a normal growing season. Of particular …

Sulfur Species Selective Adsorption Using A New Offretite Based Additive, Yira Yorsirys Aponte Torrealba

Electronic Thesis and Dissertation Repository

Fluid Catalytic Cracking (FCC) unit is one of the most important conversion processes used in petroleum refineries. Nowadays, petroleum refineries, and specifically FCC units, have to be improved. New technologies must be developed to increase the refineries revenues as well to comply with environmental regulations. One area of significant concern is the necessary in-situ FCC gasoline sulfur reduction.

In this respect, this PhD dissertation proposes a new Zn-Offretite (Zn-OFF) additive for gasoline sulfur reduction via selective adsorption in FCC units. The PhD research developed covers the preparation of the Zn-OFF zeolites and their physicochemical characterization. This physicochemical …

Kinetics Of Guaiacol Deoxygenation Using Methane Over The Pt–Bi Catalyst, Yang Xiao, Arvind Varma

Yang Xiao

Study Of The Self-Assembly Process Of Microporous Materials Using Molecular Modeling, Mohammad Navaid Khan

Doctoral Dissertations

Zeolites are an important class of materials in modern technology with applications in catalysis, separations, biosensing and microelectronics. There are over 200 different zeolite frameworks reported in literature, but only a handful have been used commercially. Understanding their self-assembly process would assist in the fabrication of new zeolites through the control of their pore size/shape, and surface area for advanced applications. With our research we aim to elucidate aspects of zeolite formation using molecular simulations. We have extended the lattice model of silica tetrahedra developed by Jin et al. [L. Jin, S. M. Auerbach and P. A. Monson J. Chem. …

Template-Assisted Hydrothermal Synthesis Of Nio@Co3O4 Hollow Spheres With Hierarchical Porous Surfaces For Supercapacitor Applications, Wen Zhou, Xue-Feng Lu, Ming-Mei Wu, Gao-Ren Li

Journal of Electrochemistry

Hollow structures have shown great potentials in a variety of important applications, such as energy conversion and storage. In order to further enhance the performance, the rational design of hollow structures with higher complexity in terms of composition and structure is highly desirable and still remains a great challenge. In this work, an efficient strategy was established for the fabrication of novel NiO@Co₃O₄ hollow spheres (HSs) with hierarchical porous surfaces by silica spheres template-assisted hydrothermal synthesis. The as-fabricated NiO@Co₃O₄ HSs showed high specific surface area of 219.68 m²·g^-1, and significant …

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 …}

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 …

Numerical Simulation On The Combustion Characteristic Of Iron Ore Sintering With Flue Gas Recirculation, Gan Wang, Zhi Wen, Guofeng Lou, Ruifeng Dou, Xunliang Liu, Fuyong Su, Sizong Zhang

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

No abstract provided.

Study Of Poisoning Mechanism Of Hg And As On V2o5–Wo3/Tio2 Scr De-Nox Catalysts, Qingcai Liu, Ming Kong, Lu Yao, Shan Ren, Jian Yang

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

No abstract provided.

Conversion Of Glycerol To Hydrocarbon Fuels Via Bifunctional Catalysts, Yang Xiao, Arvind Varma

Yang Xiao

Use Of Hydrogen Chemisorption And Ethylene Hydrogenation As Predictors For Aqueous Phase Reforming Of Lactose Over Ni@Pt And Co@Pt Bimetallic Overlayer Catalysts.Pdf, Qinghua Lai

Qinghua Lai

Hydrodeoxygenation Of Guaiacol Over Ni@Pd And Ni@Pt Bimetallic Overlayer Catalysts.Pdf, Qinghua Lai

Qinghua Lai

Esterification Of Free Fatty Acid By Selected Homogeneous And Solid Acid Catalysts For Biodiesel Production, Mohamed Kaddour

Electronic Thesis and Dissertation Repository

Biodiesel, derived from plant oils and animal fats is an attractive alternative fuel to fossil-based diesel as it is biodegradable, non-toxic, renewable, and has a low emission profile. Industrial production of biodiesel faces major challenges including limited supply of raw material and high cost of feedstock, which accounts for 60-80% of total production cost. Economic feasibility for biodiesel can be improved by using inexpensive raw materials such as waste frying oils and non-edible oils. However, these low quality feedstocks contain significant amounts of free fatty acids (FFA) which reacts with a base to produce soap hindering product separation and reduce …

Hydrothermal One-Step Synthesis Of Layered Nickel/Cobalt Double Hydroxide With Using Shape-Directing Agent And Homogeneous Precipitating Agent, Li-Wei Zhu, Yun-Hai Yan, Hui Jia, Run-Fen Liang

Journal of Electrochemistry

Nickel/cobalt double hydroxide (Ni/Co-DH) has been prepared by facile hydrothermal one-step synthesis method using hexamethylene tetramine (HMT) as a homogeneous precipitating agent and cetyltrimethylammonium bromide (CTAB) as a shape-directing agent. With the hydrolysis of HMT and the use of CTAB, the Ni/Co-DH could be synthesized without additional alkali source, and in the meantime, the Ni/Co-DH exhibited a controlled mesopore size of 13.4 nm and a large BET surface area of 93.6 m² •g^-1 . The X-ray diffraction (XRD) pattern displays that the Ni/Co-DH existed as a mixture of α-Ni(OH)₂-β-Co(OH)₂. The scanning electron microscope (SEM) …

Reactor Performances And Hydrodynamics Of Various Gas-Solids Fluidized Beds, Jiangshan Liu

Electronic Thesis and Dissertation Repository

The reactor performances and hydrodynamics were systematically studied in a multifunctional fluidized-bed system which included a bubbling fluidized bed (BFB), a turbulent fluidized bed (TFB) as well as a newly identified circulating turbulent fluidized bed (CTFB) using the same batch of activated FCC particles. Catalytic ozone decomposition was employed as the model reaction to experimentally investigate the reactor performances of BFB, TFB and CTFB. The complete mappings of ozone concentration were obtained in these fluidized beds, showing close relationship with the solids holdup distributions. In the BFBs and TFBs, the study of scale-up effect revealed that the static bed height …

Evaluation Of Voc Degradation In Photo-Catalytic Air Reactors: Tio2 Immobilization, Energy Efficiency And Kinetic Modeling, Cristina S. Lugo Vega

Electronic Thesis and Dissertation Repository

The high VOC emissions from anthropogenic sources are detrimental to both the environment and humans, contributing with ground-level ozone and particle matter formation. Heterogeneous photocatalysis provides significant potential for VOC degradation. However, the approaches to be used for photocatalyst immobilization in scaled and highly efficient photoreactors are still not well established. Furthermore, there is a lack of reported photonic efficiencies and a shortage of required methods to establish these efficiencies.

To address these issues, this PhD Dissertation reports the study of photonic efficiencies, TiO₂ immobilization on a stainless steel mesh and kinetic models in a scaled-up Photo-CREC-Air Reactor. Acetone …

Catalytic Conversion Of Fructose, Glucose And Industrial Grade Sugar Syrups To 5-Hydroxymethylfurfural, A Platform For Fuels And Chemicals, Sadra Souzanchi

Electronic Thesis and Dissertation Repository

5-hydroxymethylfurfural (HMF) as a versatile and polyfunctional compound derived from dehydration of biomass has attracted increasing attentions in research over the past decades. HMF is an important intermediate and platform chemical, which can be converted into different useful chemicals as well as the promising biofuels. It can be obtained from acid-catalyzed dehydration of different C₆-based carbohydrates such as glucose, fructose, sucrose and cellulose.

In this thesis, a cost-effective process for catalytic conversion of simple sugars (particularly glucose and fructose) and industrial grade sugar syrups to HMF was studied in a novel biphasic continuous-flow tubular reactor using inexpensive heterogeneous …

Microwave And Ultrasound Assisted Zeolitization Of Coal Fly Ash, Syed Salman Raza Bukhari

Electronic Thesis and Dissertation Repository

Coal fly ash (CFA) is a major bi-product of coal fired power plants and is a liability for coal power industry. Coal fly ash has been accumulating rapidly around the globe and has been known to be accident prone, resulting in $1.65 billion in clean-up costs and fines. Given the environmental damage CFA is capable of causing, it is a great interest for scientists to recycle this material. Utilization of novel energy such as microwave and ultrasound has been of research interest for the zeolitization of coal fly ash.

This research produced zeolites from CFA utilizing microwave and ultrasound power. …

Mechanism Of Ethanol Partial Oxidation Over Titania Supported Vanadia Catalysts: Geometric And Electronic Structure Consequences On Reaction Kinetics, Dongmin Yun

Electronic Thesis and Dissertation Repository

Supported vanadium oxide catalysts (VO_x) are used for a wide range of industrial processes. A significant amount of research has been carried on this specific system with the aim to identify the critical parameters involved in catalytic activity. The results on this relative large body of research indicate that the catalyst support plays a critical role in determining the catalytic activity of vanadia and the use of titanium dioxide as support renders a catalyst with superior activity. Studies on supported vanadia on titanium oxide (VO_x/TiO₂) have provided an understanding on support interactions that result …

A Highly Efficient Dual Rotating Disks Photocatalytic Fuel Cell With Wedged Surface Tio2 Nanopore Anode And Hemoglobin Film Cathode, Chen Yang, Yi He, Kan Li, Diwen Ying, Ye Yao, Tiantian Tang, Yalin Wang, Jinping Jia

Publications and Research

In this study, a dual rotating-disk photocatalytic fuel cell using TiO₂ on Ti plate with a wedged surface as the anode and hemoglobin (Hb) on graphite as the cathode was investigated and found to show excellent performance of simultaneous organic pollutant degradation and electricity generation. This study is based on a well-developed photocatalytic fuel cell equipped with dual rotating disks for wastewater treatment that we developed previously, and the innovation of this new device is using a hemoglobin on graphite cathode for in situ hydrogen peroxide (H₂O₂) generation. The result proved with confidence that H …

Quantification And Characterization Of Aluminum Distributions In Commercial Beta And Mordenite Zeolites By Cobalt Exchange, Rebecca L. Reitzel, Claire T. Nimlos, Rajamani Gounder

The Summer Undergraduate Research Fellowship (SURF) Symposium

The aluminum distribution throughout the zeolite framework determines the structural, ion-exchange and catalytic properties of the zeolite. Several methods have been proposed to control the Al distribution, but in order to accurately assess these methods a procedure is needed to quantify Al distribution in various zeolite frameworks. Co²⁺ ions exchange onto the zeolite framework at Al pairs, and atomic absorbance spectroscopy (AAS) can be used to quantify the number of exchanged Co²⁺ ions and, in turn, the overall number of Al pairs. Each framework exhibits differences in pore size and channel configuration which affect the equilibrium conditions needed …