DOCSLIB.ORG

Electrochemical Synthesis of Ceo2 and Ceo2/Montmorillonite Nanocomposites

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electrochemical Synthesis of Ceo2 and Ceo2/Montmorillonite Nanocomposites ANODIC ELECTROCHEMICAL SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE CERIUM OXIDE AND CERIUM OXIDE / MONTMORILLONITE NANOCOMPOSITES Qi Wang, BS., MS. Dissertation Prepared for the Degree of DOCTOR OF PHILOSOPHY UNIVERSITY OF NORTH TEXAS August 2003 APPROVED: Teresa D. Golden, Major Professor Jeffrey A. Kelber, Committee Member Michael G. Richmond, Committee Member Nandika A. D’Souza, Committee Member, Department of Materials Science and Engineering Zhibing Hu, Committee Member Ruthanne D. Thomas, Chair of the Department of Chemistry Sandra L. Terrell, Dean of the Robert B. Toulouse School of Graduate Studies Wang, Qi, Electrochemical synthesis of CeO2 and CeO2/montmorillonite nanocomposites. Doctor of Philosophy (Chemistry), December 2003, 326 pp, 24 tables, 95 illustrations, 419 references. Nanocrystalline cerium oxide thin films on metal and semiconductor substrates have been fabricated with a novel electrodeposition approach – anodic oxidation. X-ray diffraction analysis indicated that as-produced cerium oxide films are characteristic face-centered cubic fluorite structure with 5 ~ 20 nm crystal sizes. X-ray photoelectron spectroscopy study probes the non- stoichiometry property of as-produced films. Raman spectroscopy and Scanning Electron Microscopy have been applied to analyze the films as well. Deposition mode, current density, reaction temperature and pH have also been investigated and the deposition condition has been optimized for preferred oriented film formation: galvanostatic deposition with current density of –0.06 mA/cm2, T > 50oC and 7 < pH < 10. Generally, potentiostatic deposition results in random structured cerium oxide films. Sintering of potentiostatic deposited cerium oxide films leads to crystal growth and reach nearly full density at 1100oC. It is demonstrated that in-air heating favors the 1:2 stoichiometry of CeO2. Nanocrystalline cerium oxide powders (4 ~ 10 nm) have been produced with anodic electrochemical synthesis. X-ray diffraction and Raman spectroscopy were employed to investigate lattice expansion phenomenon related to the nanoscale cerium oxide particles. The pH of reaction solution plays an important role in electrochemical synthesis of cerium oxide films and powder. Cyclic voltammetry and rotation disk electrode voltammetry have been used to study the reaction mechanisms. The results indicate that the film deposition and powder formation follow different reaction schemes. Ce(III)-L complexation is a reversible process, Ce3+ at medium basic 2+ pH region (7~10) is electrochemically oxidized to Ce(OH ) 2 and then CeO2 film is deposited on the substrate. CE mechanism is suggested to be involved in the formation of films, free Ce3+ - species is coordinated with OH at high basic pH region (>10) to Ce2O3 immediately prior to electrochemically oxidation Ce2O3 to CeO2. CeO2 / montmorillonite nanocomposites were electrochemically produced. X-ray diffraction and Raman spectroscopy illustrate the retaining of FCC structure for cerium oxide. Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry of composites indicate the insertion of montmorillonite platelets into the structural matrix of cerium oxide. Sintering study of the nanocomposites demonstrates that low concentration of montmorillonite platelet coordination into cerium oxide matrix increases crystal growth rate whereas high concentration of montmoillonite in nanocomposites retards the increase of crystallite size during the densification process. ACKNOWLEDGMENTS I sincerely express my special gratitude to my academic advisor, Dr. Teresa D. Golden, for her kind guidance and great inspiration in research, also her continuous encouragement and wonderful support in my knowledge pursuit and working spirit development. I appreciate Dr. Nandika, D’Souza for her expertise and advice in the composite project. I wish to extend my acknowledgments to my committee members for their time and effort devoted to me and my research. I would like to thank Dr. Paul Braterman, Dr. Seifollah Nasrazadani (Engineering Department), Dr. Richard F. Reidy (Material Science Department), Dr. Robert M. Wallace (Material Science Department), Dr. Michael Lance (Oak Ridge National Laboratory), Ms. Laura Riester (Oak Ridge National Laboratory) and Mr. David Garrett (Biology Department) for their support and help in the material characterization. I am indebted to Dr. Oliver Chyan for his kindly providing silicon wafer for the research. Thank Mr. Williams A. Smith for making and adjusting glassware. I would like to thank Dr. Zhiping Xu, Hanjiang Dong, Dr. Prakaipetch Punchaipetch and Haritha Namduri for their helpful assistance. I truly appreciate my big sister-like colleague, Charoendee Pingsuthiwong, for her invaluable help in the research and wonderful friendship during daily life. And help from other colleagues is also appreciative. Financial support from Robert A. Welch Foundation and UNT Faculty Research Grant are highly grateful. Thanks also go to Chemistry Department of UNT for financial support as a Teaching Assistant in my first four-year graduate study and research here. ii Last but not least, I deeply appreciate my dear parents and brother for their never-ending love, support and encouragement. iii TABLE OF CONTENTS Page LIST OF TABLES ……………………………………………………………………………..viii LIST OF ILLUSTRATIONS……………………………………………………………………..xi Chapter 1. INTRODUCTION AND LITERATURE REVIEW………………………………….1 1.1 Cerium Oxide Properties, Applications, Synthesis and Characterizations………..1 1.1.1 Structure and Properties of Cerium Oxide………………………………...1 1.1.2 Practical Applications of Cerium Oxide…………………………………..7 1.1.3 Production of Cerium Oxide……………………………………………..21 1.1.4 Characterization of Cerium Oxide 1.2 Cerium Oxide / Layered Silicate Nanocomposites ……………………………...32 1.2.1 Montmorillonite Nanoclays……………………………………………...32 1.2.2 Secondary Phase Reinforcement in Composites…………………………34 1.2.3 Layered Silicate Composites …………………………………………….42 1.2.4 Synthesis of Layered Silicate Composites ………………………………44 1.2.5 Characterization of Layered Silicate and Composites …………………..46 1.3 Chapter Summaries and Dissertation Introduction ……………………………...46 1.4 Chapter References………………………………………………………………48 2. ELECTROCHEMICAL SYNTHESIS AND CHARACTERIZATION METHODS…………………………………………………………………………..64 2.1 Electrochemical Synthesis and Other Electrochemical Techniques……………..64 2.1.1 Electrochemical Synthesis……………………………………………….64 iv 2.1.2. Cyclic Votammetry (CV)………………………………………………...79 2.1.3. Rotating Disk Electrode (RDE) Method…………………………………83 2.1.4 Corrosion Electrochemistry and Corrosion Measurement……………….85 2.2 Characterization and Analysis Methods…………………………………………88 2.2.1 X-ray Diffraction (XRD)………………………………………………...88 2.2.2 X-ray Photoelectron Spectroscopy (XPS)……………………………….95 2.2.3 Infrared Spectroscopy (FTIR) and Raman Spectroscopy……………….98 2.2.4 Scanning Electron Microscopy (SEM)………………………………...103 2.2.5 Brunauer-Emmett-Teller (BET) ……………………………………….104 2.2.6 Nanoindentation………………………………………………………..106 2.2.7 Sintering Technique……………………………………………………108 2.3 Chapter Conclusions……………………………………………………………110 2.4 Chapter References……………………………………………………………..112 3. ELECTROCHEMICAL DEPOSITION OF CERIUM OXIDE FILMS…………….118 3.1 Introduction……………………………………………………………………..118 3.2 Experimental……………………………………………………………………121 3.2.1 Electrochemical Deposition of CeO2 Films…………………………….121 3.2.2 Characterization of CeO2 Films………………………………………...122 3.2.3 Property and Application Studies ……………………………………...123 3.3 Results and Discussions………………………………………………………..124 3.3.1 Deposition Conditions Investigations ………………………………….124 3.3.2 Evaluation of Particle Sizes and Lattice Strains………………………..137 3.3.3 Determination of Oxidation State with XPS……………………………141 v 3.3.4 Morphology……………………………………………………………..149 3.3.5 Sintering Studies ……………………………………………………….152 3.3.6 Corrosion Test Results………………………………………………….165 3.4 Chapter Conclusions……………………………………………………………168 3.5 Chapter References……………………………………………………………..170 4. ELECTROCHEMICAL SYNTHESIS OF NANOCRYSTALLINE CERIUM OXIDE POWDERS…………………………………………………………………………175 4.1 Introduction …………………………………………………………………….175 4.2 Experimental …………………………………………………………………..178 4.3 Results and Discussions………………………………………………………..179 4.3.1 Electrochemical Synthesis of Cerium Oxide Powders…………………179 4.3.2 Nanosized Cerium Oxide Powder Sintering……………………………184 4.3.3 Lattice Relaxation of Nanocrystalline Cerium Oxide…………………..193 4.4 Chapter Conclusions…………………………………………………………...209 4.5 Chapter References…………………………………………………………….210 5. MECHANISM STUDIES ON ELECTRODEPOSITION OF CERIUM OXIDE FILMS AND ELECTROSYNTHESIS OF CERIUM OXIDE POWDER IN SOLUTION OF CE (III) COMPLEXES…………………………………………...214 5.1 Introduction……………………………………………………………………..214 5.2 Experimental …………………………………………………………………...216 5.2.1 Electrochemical Techniques……………………………………………216 5.2.2 FTIR…………………………………………………………………….216 5.3 Results and Discussions………………………………………………………...217 vi 5.3.1 Ligand-pH Effect on Film or Powder Formation………………………217 5.3.2 Mass Transfer Study using Rotation Disk Electrode…………………...224 5.3.3 Coordination Investigation Through Varying Ligand Concentration…..228 5.4 Chapter Conclusions……………………………………………………………236 5.5 Chapter References……………………………………………………………..238 6. ELECTROCHEMICAL SYNTHESIS AND CHARACTERIZATION OF CeO2 / MONTMORILLONITE NANOCOMPOSITES…………………………………...240 6.1 Introduction ……………………………………………………………………240 6.2 Experimental …………………………………………………………………...241 6.2.1 Materials and Electrosynthesis of Composites…………………………241 6.2.2 Composite Property
Load more

Recommended publications
  • Senior Struck by Hit-And-Run Driver by Julie Carrick Dormitory Complex Toward Cleveland As of Wednesday
    B~dybuilders ,xercisl Gearing up for Hens burn w1llpower ; Tour DuPont Drexel Dragons 18-9. age 9 pages 3,9,13 page 13 FRIDAY Senior struck by hit-and-run driver By julie Carrick dormitory complex toward Cleveland as of Wednesday. pulled over on Hillside Road, then fled the Hey! said Carpentier was in shock and and Ted Neuberger Avenue, according to Newark Police Cpl. Surgeons removed two blood clots and scene of th e accident. started going into convulsions before the Staff Reporters Ted Ryser. detected two skull fractures and a fracture Heyl said he saw th e accident from the ambulance arrived. A university senior was critically injured Carpen ti er was rushed to Christiana of the left orbital of the eye, Brooks said. Lambda Chi Alpha fraternity house on West Newark police arrived three minutes Monday night when he was struck by a hit­ Hospital where he was admitted for head "We're all very concerned," he said. Main Street. Another fraternity member after 911 operators were alerted and the and-run driver at the intersection of West injuries. Physicians have put Carpentier into a called for emergency help while Hey! ambulance arrived one minute later, Heyl Main Street and Hillside Road , Newark Carpentier underwent more than four coma to reduce the swelling of his brain, covered Carpentier with a blanket until said. Police said. hours of brain surgery at 3 p.m. Tuesday, Brooks said. medical assistance arrived. The case is still under investigation. Douglas Francis Carpentier (AS 91) was sa id Dean of Students Timothy Brooks, "It's a very common and successful Eyewitness Cristi Cornell (AS 93) said: Police said they are looking for a white walking westbound on West Main Street who visiled Carpentier at the hospital with ueatment," he said.
    [Show full text]
  • Music Data Mining Presents a Variety of Approaches to Successfully Employ Data Mining Techniques for the Purpose of Music Processing
    Computer Science Chapman & Hall/CRC Music Data Mining Chapman & Hall/CRC Data Mining and Knowledge Discovery Series Data Mining and Knowledge Discovery Series The research area of music information retrieval has gradually evolved to address the challenges of effectively accessing and interacting large collections of music and associated data, such as styles, artists, Music Data lyrics, and reviews. Bringing together an interdisciplinary array of top researchers, Music Data Mining presents a variety of approaches to successfully employ data mining techniques for the purpose of music processing. Mining The book first covers music data mining tasks and algorithms and audio feature extraction, providing a framework for subsequent chapters. With a focus on data classification, it then describes a computational approach inspired by human auditory perception and examines instrument recognition, the effects of music on moods and emotions, and the connections between power laws and music aesthetics. Given the importance of social aspects in understanding music, the text addresses the use of the Web and peer-to-peer networks for both music data mining and evaluating music mining tasks and algorithms. It also discusses indexing with tags and explains how data can be collected using online human computation games. The final chapters offer a balanced exploration of hit song science as well as a look at symbolic musicology and data mining. and Tzanetakis and The multifaceted nature of music information often requires Ogihara, Li, algorithms and systems using sophisticated signal processing and machine-learning techniques to better extract useful information. An excellent introduction to the field, this volume presents state-of- the-art techniques in music data mining and information retrieval to create novel ways of interacting with large music collections.
    [Show full text]
  • Volume 20, Number 01 (January 1902) Winton J
    Gardner-Webb University Digital Commons @ Gardner-Webb University The tudeE Magazine: 1883-1957 John R. Dover Memorial Library 1-1-1902 Volume 20, Number 01 (January 1902) Winton J. Baltzell Follow this and additional works at: https://digitalcommons.gardner-webb.edu/etude Part of the Composition Commons, Ethnomusicology Commons, Fine Arts Commons, History Commons, Liturgy and Worship Commons, Music Education Commons, Musicology Commons, Music Pedagogy Commons, Music Performance Commons, Music Practice Commons, and the Music Theory Commons Recommended Citation Baltzell, Winton J.. "Volume 20, Number 01 (January 1902)." , (1902). https://digitalcommons.gardner-webb.edu/etude/466 This Book is brought to you for free and open access by the John R. Dover Memorial Library at Digital Commons @ Gardner-Webb University. It has been accepted for inclusion in The tudeE Magazine: 1883-1957 by an authorized administrator of Digital Commons @ Gardner-Webb University. For more information, please contact [email protected]. — JANUARY 1902 WITH St FOR THE TEACHER.STUDENT PRICE Si SUPPLE¬ AND LOVER OF MUSIC FIFTEEN MENT St THEO. PRESSER PUBL1SHER.PHILADA,PA CENTS 1 the etude CONTENTS H. B. STEVENS COMPANY Music of Medium Difficulty T HE ETUDE January, 19^2 PUBLISHERS AND IMPORTERS OF MUSIC ‘THE ETUDE,” lor TEACHERS new works Educational Works 211 TR-EMONT STR-EET^ - - BOSTON Joseph Hofmann on Piano Technic and Piano Prac- G. SCHIRMER PUBLISHED BY Fdlix Borowski, director of composition Chicago Seed Thoughts for Musicians. PIANO SOLOS. FOUR HANDS. SIX HANDS. Musical College. Grieg said, m 1894, that Mr. Bor¬ In Mozartland with Old Fogy. owski was the coming composer, and the prophecy Problems of Music Education.
    [Show full text]
  • The Simulation, Development, and Testing of a Staged
    THE SIMULATION, DEVELOPMENT, AND TESTING OF A STAGED CATALYTIC MICROTUBE IGNITION SYSTEM By MATTHEW CHARLES DEANS Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Thesis Advisors: Dr. James T’ien & Dr. Steven J. Schneider Department of Mechanical and Aerospace Engineering CASE WESTERN RESERVE UNIVERSITY January, 2013 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the dissertation of Matthew Charles Deans for the Doctor of Philosophy in Aerospace Engineering degree*. (signed) James T’ien (Chair of the Committee) Steven Schneider Paul Barnhart Yasuhiro Kamotani Donald Feke (date) 7/23/2012 *We also certify that written approval has been obtained for any proprietary material contained therein. i Dedication: I would like to dedicate this work to my fiancée, Leah. Thank you for being there through my stress and struggles and for supporting me even with your own sacrifices. I will always appreciate everything you’ve ever done for me! ii Table of Contents Contents Dedication: ..................................................................................................................................... ii List of Tables: ................................................................................................................................. 4 List of Figures: ............................................................................................................................... 5 Acknowledgements: ...................................................................................................................
    [Show full text]
  • Displaying Abstracts
    HONORS COLLABORATIVE PRESENTATION ABSTRACT Brenda Benkenstein, Julia Bitterly, Josh Coursey, Eddie Espineli, Taylor Fayle, Emiliano Herrera III, Stephanie Hollomon, Jeanette Kutach, Alicia Macken, Amber Martinez, Daniel Massey, Patrick Nguyen, Juanita Sena, Carolyn Stalzer, Michael Wells. FACULTY SPONSOR: Rev. Anthony E. Giampietro, C.S.B., The most fundamental unit of society is the family, the institution whose purpose and structure shape an individual through moral, practical and intellectual education. Over the past few decades, however, society has lost sight of the ideal structure of family and its true purpose. This problem is evidenced by growing divorce rates, single-parent homes and absent fathers, poor interfamilial relationships, increased sexual promiscuity, the escalation of violence, and the retreat of youth into pop culture and gangs. To confront these and other societal ills, we will first examine why these situations are harmful to the individual, family, and society. In addition, we will explore obstacles challenging the contemporary family, including the American concept of individuality, materialism, the rise of women in the workplace, reproductive technology, and the media. The objective of this collaborative and interdisciplinary project is to provide viable solutions for change within the limits of every family’s capacity, regardless of racial, religious, or socioeconomic background. We not only embrace these solutions in our own lives, but also encourage each member of society to do the same, so that we may pass
    [Show full text]