DOCSLIB.ORG

Investigation, Design, and Commercialization of Actively-Enhanced Solid-State Gas Sensor Arrays

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Investigation, Design, and Commercialization of Actively-Enhanced Solid-State Gas Sensor Arrays INVESTIGATION, DESIGN, AND COMMERCIALIZATION OF ACTIVELY-ENHANCED SOLID-STATE GAS SENSOR ARRAYS By BRYAN MICHAEL BLACKBURN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2009 1 © 2009 Bryan Michael Blackburn 2 To my family and friends for always believing in me 3 ACKNOWLEDGMENTS I would like to thank my colleagues and mentors over my many years of study and personal growth. I would also like to thank my parents and grandparents for fostering in me from an early age a philosophy for continuous learning and improvement. This includes the pursuit of knowledge from all fronts: engineering, science, mathematics, business, religion, literature, and more. To my fiancée, Kaitlin, I am thankful for the many years of understanding and patience as I worked towards this and future goals. In and around the lab, I would like to thank Dr. Hee-Sung Yoon, Nick Vito, and Patrick Wanninkhof for helping me with various aspects of my work. For keeping me calm during times of high stress, I would like to thank Cynthia Kan. I would also like to thank my brother, Jeremy, for providing a constant source of healthy competition during our childhood. I would like to thank Dr. Scott Perry for many useful talks regarding surface science and the use of his equipment. Furthermore, I would like to thank his graduate student, Greg Dudder, for working with me on some of the surface science experiments and teaching me about photoelectron spectroscopy. I would also like to thank Dr. Juan Nino and Dr. Enrico Traversa for teaching me valuable concepts during my time as a graduate student. I would be remiss not to thank Dr. Toshi Nishida for serving as the initial source of inspiration while I was an undergraduate student in electrical engineering that lead me to pursue a doctorate degree; he has since continued to motivate me and I look forward to the possibility of working with him on projects in the future. Finally, I would like to thank my advisor Dr. Eric Wachsman and mentor P.N. ‘Vaidy’ Vaidyanathan for invaluable guidance and giving me the opportunity to prove myself as an engineer, scientist, and businessman. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES.........................................................................................................................10 LIST OF FIGURES .......................................................................................................................11 ABSTRACT...................................................................................................................................17 CHAPTER 1 INTRODUCTION ...................................................................................................................19 1.1 Small, Robust, Low-Cost Selective Multifunctional Gas Sensors ...................................19 1.1.1 Significance............................................................................................................19 1.1.1.1 Energy efficiency.....................................................................................19 1.1.1.2 Pollutant emissions..................................................................................21 1.1.1.3 Process control.........................................................................................22 1.1.1.4 Noninvasive disease diagnostics and monitoring....................................23 1.1.2 Key Applications for Advanced Gas Sensor Technology .....................................23 1.1.2.1 Energy production industry .....................................................................24 1.1.2.2 Transportation, heavy equipment, and materials handling industries .....26 1.1.2.3 Materials and chemical processing industries .........................................28 1.1.2.4 Medical industry......................................................................................29 1.1.2.5 Other important applications ...................................................................31 1.1.3 General Requirements of Gas Sensors...................................................................32 1.1.3.1 Sensitivity................................................................................................32 1.1.3.2 Selectivity................................................................................................32 1.1.3.3 Response time..........................................................................................33 1.1.3.4 Repeatability, accuracy, and resolution...................................................33 1.1.3.5 Signal-to-noise ratio ................................................................................34 1.2 Research Objectives..........................................................................................................34 1.2.1 Sensor Arrays for Detecting Multiple Gas Species ...............................................34 1.2.2 Thermal Enhancements..........................................................................................35 1.2.3 Electric-Field Enhancements .................................................................................35 1.2.4 Surface Science Analysis.......................................................................................35 1.2.5 Improved R&D and Commercialization Efforts....................................................36 2 BACKGROUND AND LITERATURE REVIEW .................................................................39 2.1 Gas Sensors.......................................................................................................................39 2.1.1 General Issues ........................................................................................................40 2.1.2 Solid-State Gas Sensor Technology.......................................................................41 2.1.2.1 Thermal sensors.......................................................................................41 2.1.2.2 Mass sensors............................................................................................41 5 2.1.2.3 Optical sensors.........................................................................................41 2.1.2.4 Electrochemical sensors ..........................................................................41 2.1.3 Electrochemical Gas Sensor Theory......................................................................43 2.1.3.1 Principles of electronic and ionic conduction .........................................43 2.1.3.2 Principles of solid-state electrochemistry................................................43 2.1.3.3 Electrochemical promotion .....................................................................47 2.1.3.4 Semiconducting oxides............................................................................48 2.1.3.5 Mixed potential theory ............................................................................50 2.1.3.6 Differential electrode equilibria theory ...................................................51 2.1.3.7 Electrolyte and gas sensing electrode materials ......................................52 2.2 Related Work....................................................................................................................54 2.2.1 Techniques for Studying Gas Sensor Mechanisms................................................54 2.2.1.1 Conductivity measurements ....................................................................54 2.2.1.2 Controlled-potential techniques...............................................................55 2.2.1.3 Electrochemical impedance spectroscopy...............................................55 2.2.1.4 Mass spectrometry...................................................................................56 2.2.1.5 Kelvin probe work function measurements.............................................56 2.2.1.6 Electron spectroscopic techniques...........................................................57 2.2.2 Electric-Field Effects in Surface Processes and Solid-State Devices....................58 2.2.3 Other Important Electrolytes and Sensing Electrodes ...........................................59 3 DIFFERENTIAL ELECTRODE TEMPERATURE EFFECT ...............................................65 3.1 Introduction.......................................................................................................................65 3.2 Background.......................................................................................................................65 3.3 Experimental.....................................................................................................................67 3.3.1 Sample Preparation ................................................................................................68 3.3.2 Test Setup...............................................................................................................69 3.3.3 Testing Procedures.................................................................................................69 3.3.4 3D Reconstruction of Sensing Electrodes with FIB/SEM.....................................70 3.4 Results and Discussion .....................................................................................................71 3.4.1 Proof of Concept....................................................................................................71
Load more

Recommended publications
  • Integrated Chemical Microsensor Systems in CMOS Technology by A
    microtechnology and mems microtechnology and mems Series Editor: H. Baltes H. Fujita D. Liepmann The series Microtechnology and MEMS comprises text books, monographs, and state-of-the-art reports in the very active field of microsystems and microtech- nology. Written by leading physicists and engineers, the books describe the basic science, device design, and applications. They will appeal to researchers, engineers, and advanced students. Mechanical Microsensors By M. Elwenspoek and R. Wiegerink CMOS Cantilever Sensor Systems Atomic Force Microscopy and Gas Sensing Applications By D. Lange, O. Brand, and H. Baltes Micromachines as Tools for Nanotechnology Editor: H. Fujita Modelling of Microfabrication Systems By R. Nassar and W. Dai Laser Diode Microsystems By H. Zappe Silicon Microchannel Heat Sinks Theories and Phenomena By L. Zhang, K.E. Goodson, and T.W. Kenny Shape Memory Microactuators By M. Kohl Force Sensors for Microelectronic Packaging Applications By J. Schwizer, M. Mayer and O. Brand Integrated Chemical Microsensor Systems in CMOS Technology By A. Hierlemann A. Hierlemann Integrated Chemical Microsensor Systems in CMOS Technology With 125 Figures 123 Professor Dr. Andreas Hierlemann Physical Electronics Laboratory ETH Hoenggerberg, HPT-H 4.2, IQE 8093 Zurich Switzerland Email: [email protected] Series Editors: Professor Dr. H. Baltes ETH Zürich, Physical Electronics Laboratory ETH Hoenggerberg, HPT-H6, 8093 Zürich, Switzerland Professor Dr. Hiroyuki Fujita University of Tokyo, Institute of Industrial Science 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan Professor Dr. Dorian Liepmann University of California, Department of Bioengineering 466 Evans Hall, #1762, Berkeley, CA 94720-1762, USA ISSN 1439-6599 ISBN 3-540-23782-8 Springer Berlin Heidelberg New York LibraryofCongressControlNumber:2004114045 This work is subject to copyright.
    [Show full text]
  • Quantum Mechanics Electromotive Force
    Quantum Mechanics_Electromotive force . Electromotive force, also called emf[1] (denoted and measured in volts), is the voltage developed by any source of electrical energy such as a batteryor dynamo.[2] The word "force" in this case is not used to mean mechanical force, measured in newtons, but a potential, or energy per unit of charge, measured involts. In electromagnetic induction, emf can be defined around a closed loop as the electromagnetic workthat would be transferred to a unit of charge if it travels once around that loop.[3] (While the charge travels around the loop, it can simultaneously lose the energy via resistance into thermal energy.) For a time-varying magnetic flux impinging a loop, theElectric potential scalar field is not defined due to circulating electric vector field, but nevertheless an emf does work that can be measured as a virtual electric potential around that loop.[4] In a two-terminal device (such as an electrochemical cell or electromagnetic generator), the emf can be measured as the open-circuit potential difference across the two terminals. The potential difference thus created drives current flow if an external circuit is attached to the source of emf. When current flows, however, the potential difference across the terminals is no longer equal to the emf, but will be smaller because of the voltage drop within the device due to its internal resistance. Devices that can provide emf includeelectrochemical cells, thermoelectric devices, solar cells and photodiodes, electrical generators,transformers, and even Van de Graaff generators.[4][5] In nature, emf is generated whenever magnetic field fluctuations occur through a surface.
    [Show full text]
  • Fundamentals of Electrochemistry
    ffirs.qxd 10/29/2005 11:56 AM Page iii FUNDAMENTALS OF ELECTROCHEMISTRY Second Edition V. S. BAGOTSKY A. N. Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences Moscow, Russia Sponsored by THE ELECTROCHEMICAL SOCIETY, INC. Pennington, New Jersey A JOHN WILEY & SONS, INC., PUBLICATION ftoc.qxd 10/29/2005 12:01 PM Page xiv ffirs.qxd 10/29/2005 11:55 AM Page i FUNDAMENTALS OF ELECTROCHEMISTRY ffirs.qxd 10/29/2005 11:55 AM Page ii THE ELECTROCHEMICAL SOCIETY SERIES The Electrochemical Society 65 South Main Street Pennington, NJ 08534-2839 http://www.electrochem.org A complete list of the titles in this series appears at the end of this volume. ffirs.qxd 10/29/2005 11:56 AM Page iii FUNDAMENTALS OF ELECTROCHEMISTRY Second Edition V. S. BAGOTSKY A. N. Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences Moscow, Russia Sponsored by THE ELECTROCHEMICAL SOCIETY, INC. Pennington, New Jersey A JOHN WILEY & SONS, INC., PUBLICATION ffirs.qxd 10/29/2005 11:56 AM Page iv Copyright © 2006 by John Wiley & Sons, Inc. All rights reserved Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com.
    [Show full text]
  • Introduction to Fuel Cells: Fundamentals of Electrochemical Kinetics, Thermodynamics and Solid State Chemistry (II) for the Experienced
    Introduction to fuel cells: Fundamentals of electrochemical kinetics, thermodynamics and solid state chemistry (II) for the experienced Mogens Mogensen Fuel Cells and Solid State Chemistry Risø National Laboratory Technical University of Denmark P.O. 49, DK-4000 Roskilde, Denmark Tel.: +45 4677 5726; [email protected] Contents • Basics of electromotive force, cell voltage and reversibility • The course of electric potential through a cell - simplified • Potential concepts - energy and voltage • Electric potentials in more details • Examples - the potential and oxygen partial pressure through a YSZ based SOC • Polarisation of the cell and electrode overpotential types • Measurements of electrolyte resistance, reaction resistance and electrode overvoltage by EIS • Three electrode set-up and its problems • Other strategies • Electrode mechanisms • Recommended literature LargeSOFC Summer School 2010 Basics A fuel cell is a galvanic cell also called an electrochemical cell The relation between the chemical energy, ΔG (Gibbs free energy of reaction) of a cell reaction and the equilibrium (ideal) electrical voltage, also called the electromotive force, Emf, of the cell is given by -ΔG = n∙F∙Emf n is the number of electrons exchanged in the total reaction, and F is The Faraday constant = 96485 As/mol LargeSOFC Summer School 2010 Basics Important: ΔG and n must refer to the same reaction scheme! Example 1: 2- - H2 + O ' H2O + 2e - 2- ½O2 + 2e ' O H2 + ½O2 ' H2O 0 n = 2 and ΔG 298 = - 286 kJ/mol H2 Example 2: 2- - 2H2 + 2O ' 2H2O + 4e - 2- O2 + 4e ' 2O 2H2 + O2 ' 2H2O 0 n = 4 and ΔG 298 = - 572 kJ/mol O2 LargeSOFC Summer School 2010 Basics At standard conditions (25 °C and 1 atm): Emf = -ΔG0/(nF) = - (- 286 kJ/mol)/(2*96485 As/mol) = - (- 572 kJ/mol)/(4*96485 As/mol) = 1.23 V ΔG = ΔG0 + RTlnK, K is the constant in the law of mass action This gives us the Nernst equation: RT P EE=+ ln HO2 0 nF P P HO22 LargeSOFC Summer School 2010 Basics The cell voltage may deviate from the theoretical Nernst voltage.
    [Show full text]
  • Contact Potentials, Fermi Level Equilibration, and Surface Charging Pekka Peljo,*,† Joséa
    Article pubs.acs.org/Langmuir Contact Potentials, Fermi Level Equilibration, and Surface Charging Pekka Peljo,*,† JoséA. Manzanares,‡ and Hubert H. Girault† † Laboratoire d’Electrochimie Physique et Analytique, École Polytechnique Fedéralé de Lausanne, EPFL Valais Wallis, Rue de l’Industrie 17, Case Postale 440, CH-1951 Sion, Switzerland ‡ Department of Thermodynamics, Faculty of Physics, University of Valencia, c/Dr. Moliner, 50, E-46100 Burjasot, Spain *S Supporting Information ABSTRACT: This article focuses on contact electrification from thermodynamic equilibration of the electrochemical potential of the electrons of two conductors upon contact. The contact potential difference generated in bimetallic macro- and nanosystems, the Fermi level after the contact, and the amount and location of the charge transferred from one metal to the other are discussed. The three geometries considered are spheres in contact, Janus particles, and core−shell particles. In addition, the force between the two spheres in contact with each other is calculated and is found to be attractive. A simple electrostatic model for calculating charge distribution and potential profiles in both vacuum and an aqueous electrolyte solution is described. Immersion of these bimetallic systems into an electrolyte solution leads to the formation of an electric double layer at the metal−electrolyte interface. This Fermi level equilibration and the associated charge transfer can at least partly explain experimentally observed different electrocatalytic, catalytic, and optical properties of multimetallic nanosystems in comparison to systems composed of pure metals. For example, the shifts in the surface plasmon resonance peaks in bimetallic core−shell particles seem to result at least partly from contact charging. ■ INTRODUCTION of an electric double layer around the particles.
    [Show full text]
  • The Partition of Salts (I) Between Two Immiscible Solution Phases and (Ii) Between the Solid Salt Phase and Its Saturated Salt Solution
    ChemTexts (2020) 6:17 https://doi.org/10.1007/s40828-020-0109-0 (0123456789().,-volV)(0123456789().,-volV) LECTURE TEXT The partition of salts (i) between two immiscible solution phases and (ii) between the solid salt phase and its saturated salt solution Fritz Scholz1 · Heike Kahlert1 · Richard Thede1 Received: 17 December 2019 / Accepted: 2 March 2020 / Published online: 24 April 2020 © The Author(s) 2020 Abstract The partition of salts between two polar immiscible solvents results from the partition of the cations and anions. Because electroneutrality rules in both phases, the partition of cations is affected by that of anions, and vice versa. Thus, the partition of a salt is determined by the chemical potentials of cations and anions in both phases, and it is limited by the boundary condition of electroneutrality. Whereas the partition of neutral molecules does not produce a Galvani potential difference at the interface, the partition of salts does. Here, the equations to calculate this Galvani potential difference are derived for salts of the general composition CatðzCatÞþAnðzAnÞÀ and for uni-univalent salts CatþAnÀ. The activity of a mCat mAn specific ion in a particular phase can thus be purposefully tuned by the choice of a suitable counterion. Finally, the distribution of a salt between its solid phase and its saturated solution is also presented, together with a discussion of the Galvani potential difference across the interface of the two phases. Graphical abstract Dear Plus, but I do Come over, beloved not like your Minus, we need your phase! charge! Phase α Phase β Keywords Partition · Partition constant · Ion · Salt · Electrolyte · Galvani potential difference · Ion adsorption · Fajans · Precipitation · Titration List of symbols Latin symbols a Activity Fritz Scholz and Heike Kahlert equally contributed as authors.
    [Show full text]
  • Physical and Interfacial Electrochemistry 2013 Lecture 4
    jj 0 jj Physical and Interfacial Electrochemistry 2013 Lecture 4. Electrochemical Thermodynamics Module JS CH3304 MolecularThermodynamics and Kinetics Thermodynamics of electrochemical systems Thermodynamics, the science of possibilities is of general utility. The well established methods of thermodynamics may be readily applied to electrochemical cells. We can readily compute thermodynamic state functions such as G, H and S for a chemical reaction by determining how the open circuit cell potential Ecell varies with solution temperature. We can compute the thermodynamic efficiency of a fuel cell provided that G and H for the cell reaction can be evaluated. M Ox,Red Red',Ox' M ' We can also use measurements of equilibrium cell potentials to - + determine the concentration of Anode a redox active substance present Cathode Oxidation Reduction at the electrode/solution interface. e- loss This is the basis for potentiometric e- gain chemical sensing. LHS RHS 1 Standard Electrode Potentials Standard reduction potential (E0) is the voltage associated with a reduction reaction at an electrode when all solutes are 1 M and all gases are at 1 atm. Reduction Reaction - + 2e + 2H (1 M) 2H2 (1 atm) E0 = 0 V Standard hydrogen electrode (SHE) Measurement of standard redox potential E0 for the redox couple A(aq)/B(aq). electron flow Ee reference indicator H2 in electrode Pt electrode SHE P t A(aq) H2(g) H+(aq) B(aq) test redox couple salt bridge E0 provides a quantitative measure for the thermodynamic tendency of a redox couple to undergo reduction or oxidation. 2 Standard electrode potential • E0 is for the reaction as written •The more positive E0 the greater the tendency for the substance to be reduced • The half-cell reactions are reversible •The sign of E0 changes when the reaction is reversed • Changing the stoichiometric coefficients of a half-cell reaction does not change the value of E0 19.3 We should recall from our CH1101 The procedure is simple to apply.
    [Show full text]
  • INTERPHASES in SYSTEMS of CONDUCTING PHASES (Recommendations 1985) (Supersedes Provisional Version Published 1983)
    Pure & App!. Chem., Vol. 58, No. 3, pp. 437—454, 1986. Printed in Great Britain. ©1986IUPAC INTERNATIONALUNION OF PURE AND APPLIED CHEMISTRY PHYSICAL CHEMISTRY DIVISION COMMISSION ON ELECTROCHEMISTRY* INTERPHASES IN SYSTEMS OF CONDUCTING PHASES (Recommendations 1985) (Supersedes provisional version published 1983) Prepared for publication by S. TRASATFI and R. PARSONS2 1Università di Milano, Italy 2University of Southampton, UK *Membership of the Commission for 1979—85 during which the recommendations were prepared was as follows: Chairman: 1979—81 R. Parsons (France); 1981—83 K. E. Heusler (FRG); 1983—85 S. Trasatti (Italy); Vice-Chairman: 1979—81 A. Bard (USA); 1981—83 S. Trasatti (Italy); Secretary: 1979—83 J. C. Justice (France); 1983—85 K. Niki (Japan); Titular andAssociate Members: J. N. Agar (UK; Associate 1979—85); A. Bard (USA; Titular 1981—83); A. Bewick (UK; Associate 1983—85); E. Budevski (Bulgaria; Associate 1979—85); L. R. Faulkner (USA; Titular 1983—85); G. Gritzner (Austria; Associate 1979—83, Titular 1983—85); K. E. Heusler (FRG; Titular 1979— 81, Associate 1983—85); H. Holtan (Norway; Associate 1979—83); N. Iblt (Switzerland; Associate 1979—81); J. C. Justice (France; Associate 1983—85); M. Keddam (France; Associate 1979—83); J. Koryta (Czechoslovakia; Associate 1983—85); J. K&at (Czechoslovakia; Titular 1979—81); D. Landolt (Switzerland; Titular 1983—85); V. M. M. Lobo (Portugal; Associate 1983—85); R. Memming (FRG; Associate 1979—83, Titular 1983—85); B. Miller (USA; Associate 1979—85); K. Niki (Japan; Titular 1979—83); R. Parsons (France; Associate 1981—85); 0. A. Petni (USSR; Associate 1983—85); J. A. Plambeck (Canada; Associate 1979—85); Y.
    [Show full text]
  • Chemical Sensors an Introduction for Scientists and Engineers Peter Gründler Chemical Sensors
    Chemical Sensors An Introduction for Scientists and Engineers Peter Gründler Chemical Sensors An Introduction for Scientists and Engineers With 179 Figures and 25 Tables 123 Peter Gründler Hallwachsstraße 5 D-01069 Dresden Germany e-mail: [email protected] Library of Congress Control Number: 2006933730 ISBN 978-3-540-45742-8 Springer Berlin Heidelberg New York DOI 10.1007/978-3-540-45743-5 This work is subject to copyright. All rights reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable for prosecution under the German Copyright Law. Springer is a part of Springer Science+Business Media springer.com © Springer-Verlag Berlin Heidelberg 2007 The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Product liability: The publishers cannot guarantee the accuracy of any information about dosage and application contained in this book. In every individual case the user must check such information by consulting the relevant literature. Cover design: KünkelLopka GmbH, Heidelberg Typesetting and production: LE-TEX Jelonek, Schmidt & Vöckler GbR, Leipzig, Germany Printed on acid-free paper 52/3100/YL - 5 4 3 2 1 0 Preface When this book appeared in German, its main task was to bridge the gap between the traditional ways of thinking of scientists and engineers.
    [Show full text]
  • 2.4 Electrochemical Cell with a Liquid Junction Potential
    1.1 1 Potential Difference between two metals in a cell without liquid junction 2 Potential difference between two metals in a cell with liquid junction 3 4 5 1.2 • t 6 7 8 9 10 2.Introduction to potentiomentry 2.1. Galvani potential and electrochemical potential Zero energy – charged particle in vacuum at infinite separation from a charged phase Basic concepts _ 1. Electrochemical potential - μ work done when a charged particle is transferred from infinite separation in vacuum to the interior of a charged phase 2. Chemical potential - μ work done when a charged particle is transferred from infinite separation in vacuum to the interior of a phase stripped from the charged surface layer 3. Inner potential ( Galvani potential ) - φ work done when a charged particle is transferred from infinite separation in vacuum across a surface shell which contains an excess charge and oriented dipoles 11 _ μμ=+e φ 12 The inner potential may be regarded as a sum of: 1) Potential created by the excess charge, the so called outer potential or Volta potential, denoted as Ψ. For a charge q on a sphere of radius a: q ψ = a 2. Potential created by oriented dipoles with dipole moment p referred to as surface potential, denoted as χ and equal to : χ =4πNp ε / Therefore the inner potential is equal to: φ =ψ +χ 13 Thermodynamic relationships In a charged system the inner potential φ is an additional independent variable of the total Gibbs free energy: G = f (p,T,nj,φ) Basic thermodynamic definitions: _ 1.
    [Show full text]
  • Computation of Electrode Potentials and Alignment of Electronic Energy
    Computation of Electrode Potentials and Alignment of Electronic Energy Levels Jun Cheng, Marialore Sulpizi, Michiel Sprik ([email protected]) University of Cambridge Contents 1. Reversible and ideally polarizable electrodes 2. Absolute electrode potentials and workfunctions 3. Alignment of vertical and adiabatic energy levels Key source textbooks: F Liquids, Solutions, and Interfaces, W .R. Fawcett (Oxford University Press). BF Electrochemical Methods, A. J .Bard and L R. Faulkner (Wiley) B Fundamentals of Electrochemistry, V. S. Bagotsky (Wiley) G Physical Electrochemistry, E. Gileadi (Wiley). 1.1: Pt(111)/water interface at potential of zero charge -6 Three kind of levels just outside vacuum 0 Electronic levels that are -4 electrode potentials CBM -2 Electronic levels that are -2 not electrode potentials Electrode potentials that -4 0 Fermi are not electronic levels level − -6 2 OH/OH OH/H O potential vs SHE [V] 2 -8 4 energy relative to vacuum [eV] VBM -10 6 Pt (111) water All experimental data 1.2: Pt(111)/water interface at potential of zero charge -6 More electronic levels just outside vacuum 0 IP: Vertical ionization -4 potential of the OH− ion. CBM -2 EA: Vertical electron -2 affinity of OH• radical. -EA -4 0 Fermi λ level − -6 2 OH/OH potential vs SHE [V] λ -8 4 -IP energy relative to vacuum [eV] VBM -10 6 Pt (111) water All experimental data 1.3: The two modes of an electrochemical cell load source I U U anode e e cathode cathode e e anode I I K K K K e e e e Cl Cl ½H2 H ½ 2 H ½H2 Cl ½Cl2 Oxidation Reduction Reduction Oxidation
    [Show full text]
  • The University of Oklahoma Graduate College a Method for Determining Liquid-Junction Electromotive Force by Contact Potential Me
    THE UNIVERSITY OF OKLAHOMA GRADUATE COLLEGE A METHOD FOR DETERMINING LIQUID-JUNCTION ELECTROMOTIVE FORCE BY CONTACT POTENTIAL MEASUREMENTS A DISSERTATION SUBMITTED TO THE GRADUATE FACULTY in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY BY MARVIN MARTIN MUELLER Norman, Oklahoma 1959 A METHOD FOR DETERMINING LIQUID-JUNCTION ELECTROMOTIVE FORCE BY CONTACT POTENTIAL MEASUREMENTS A^ROTOS BY ÿ "5 ^ 1 / ‘ m , . DISSERTATION CŒiMITTEE ACKNOWLEDGMENTS It is with pleasure that I declare my indebtedness to the late Professor William Schriever who initially suggested that we make an at­ tempt at measuring phase-boundary potential differences. His friendly interest and encouragement, specifically in the earlier portion of the research, were of considerable benefit. In particular, it should be mentioned that the idea of using a liquid-quadrant electrometer is due to Professor Schriever. To Professor J. Rud Nielsen goes my gratitude for his interest in the latter stages of the research and for his concern in seeing that the apparatus not fall into desuetude after this work is terminated. To the physics shop and, especially, Mr. Jim Hood go ny thanks and commendation for a job well and patiently done. Mr. Hood's care and concern over many months is manifest in the good mechanical performance of the final apparatus. Finally and most personally, 1 wish to record ray heartfelt grat­ itude for the myriad ways in which ny wife, Elvira, has been of help dur­ ing the years of this research. Without her assistance this work would not have been carried out. iii TABLE OF CONTENTS Page LIST OF TABLES .................................................
    [Show full text]