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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. 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For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com. Library of Congress Cataloging-in-Publication Data: Bagotsky, V. S. (Vladimir Sergeevich) Fundamentals of electrochemistry / V. S. Bagotsky—2nd ed. p. cm. Includes bibliographical references and index. ISBN-13 978-0-471-70058-6 (cloth : alk. paper) ISBN-10 0-471-70058-4 (cloth : alk. paper) 1. Electrochemistry I. Title. QD553.B23 2005 541⬘.37—dc22 2005003083 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 ftoc.qxd 10/29/2005 12:01 PM Page v CONTENTS Contributors xv Preface to the Second Edition xvii Preface to the First Edition xix List of Photographs xxii Abbreviations xxiii Symbols xxv PART I BASIC CONCEPTS 1 1. Electric Currents in Ionic Conductors 3 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Various Types of Conductors, 3 Ions in Electrolyte Solutions, 4 Conductivity of Electrolyte Solutions, 5 Circuits Involving Ionic Conductors. Electrodes, 9 Passage of Current Through Electrodes. Electrode Reactions, 10 Classification of Electrodes and Electrode Reactions, 12 Faraday’s Laws, 15 Equations for Mass Balance, 16 Sign Convention for Currents and Fluxes, 18 2. Electrode Potentials 2.1 2.2 2.3 2.4 2.5 Interfacial Potential Differences (Galvani Potentials), 20 Exchange Currents, 23 Open-Circuit Voltages, 24 Electrode Potentials, 26 Cell Voltage at Nonzero Current, 29 3. Thermodynamics of Electrochemical Systems 3.1 3.2 19 33 Conventional and Undefined Parameters, 33 Thermodynamic Functions in Electrochemistry, 34 v ftoc.qxd 10/29/2005 vi 12:01 PM Page vi CONTENTS 3.3 3.4 3.5 3.6 Thermodynamic Activity, 36 Equations for the EMF of Galvanic Cells, 39 Concentration Dependence of Electrode Potentials, 41 Special Thermodynamic Features of Electrode Potentials, 46 4. Mass Transfer in Electrolytes 51 4.1 Basic Laws of Ionic Diffusion in Solutions, 51 4.2 Limiting Diffusion Currents in Electrolytes, 53 4.3 Ionic Transport by Migration and Diffusion, 55 4.4 Convective Transport, 60 5. Phase Boundaries (Interfaces) Between Miscible Electrolytes 5.1 5.2 5.3 5.4 5.5 69 Types of Interfaces Between Electrolytes, 69 Potentials Between Similar Electrolytes (Diffusion Potentials), 71 Distribution of the Ions Between Dissimilar but Miscible Electrolytes, 73 Distribution of Ions in Cells with Membrane, 75 Galvanic Cells with Transference, 76 6. Polarization of Electrodes 79 6.1 Basic Concepts, 79 6.2 Laws of Activation Polarization, 82 6.3 Diffusional Concentration Polarization, 89 6.4 Superposition of Concentration and Activation Polarization, 93 7. Aqueous Electrolyte Solutions 99 7.1 Electrolytic Dissociation, 99 7.2 Ionic Solvation (Hydration) in Solutions, 106 7.3 Activity of Real Electrolyte Solutions, 112 7.4 Physical Theories of Ion–Ion Interactions, 116 8. Nonaqueous Electrolytes 8.1 Different Types of Electrolytes and Their Practical Utilization, 127 8.2 Nonaqueous Electrolyte Solutions, 128 8.3 Ionically Conducting Melts, 131 8.4 Inorganic Solid Electrolytes, 134 127 ftoc.qxd 10/29/2005 12:01 PM Page vii CONTENTS 9. Electron Work Functions and Volta Potentials vii 139 9.1 Surface Potential of a Phase, 139 9.2 Work Functions, 140 9.3 Volta Potentials, 143 9.4 Two Problems in Electrochemistry, 144 10. Structure and Properties of Surface Layers 10.1 10.2 10.3 10.4 10.5 10.6 Electrical Structure of Interphases, 148 Adsorption Phenomena, 156 Thermodynamics of Surface Phenomena, 162 Mercury Electrode Surface, 169 Platinum Electrode Surface, 172 Surfaces of Other Electrodes, 178 11. Transient Processes 11.1 11.2 11.3 12.3 12.4 12.5 PART II 191 Reference Electrodes, 192 Voltage and Electrode Potential Measurements (Potentiometry), 195 Steady-State Polarization Measurements, 195 Transient (Pulse) Measurements, 199 Impedance Measurements, 207 KINETICS OF ELECTROCHEMICAL REACTIONS 13. Multistep Electrode Reactions 13.1 13.2 13.3 13.4 13.5 13.6 13.7 181 Evidence for Transient Conditions, 181 Transient Diffusion to Electrodes of Large Size, 182 Transient Diffusion to Electrodes of Finite Size, 188 12. Electrochemical Research Techniques 12.1 12.2 147 Intermediate Reaction Steps, 219 Rate-Determining Step, 220 Two-Step Electrochemical Reactions, 222 Complex Electrochemical Reactions, 227 Reactions with Homogeneous Chemical Steps, 229 Reactions with Mediators, 233 Parallel Electrode Reactions, 235 217 219 ftoc.qxd 10/29/2005 viii 12:01 PM Page viii CONTENTS 14. Some Aspects of Electrochemical Kinetics 239 14.1 Energy of Activation, 239 14.2 Kinetic Influence of the Electric Double Layer, 245 14.3 Kinetic Influence of Adsorption, 248 14.4 Special Features of Reactions at Semiconductor Electrodes, 250 14.5 Reactions Producing a New Phase, 252 15. Reactions at Nonconsumable Electrodes 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 Simple Electrochemical Reactions, 261 Hydrogen Evolution and Ionization, 263 Reactions Involving Oxygen, 272 Reactions Involving Chlorine and Other Halogens, 277 Reactions Involving Organic Substances, 280 Reactions at High Anodic Potentials, 288 Reaction of Carbon Dioxide Reduction, 291 Reaction of Nitrogen Reduction, 294 16. Reactions Involving Metals 16.1 16.2 16.3 16.4 16.5 16.6 PART III APPLIED ASPECTS OF ELECTROCHEMISTRY 319 321 Chlor-Alkali Electrolysis, 321 Water Electrolysis, 323 Electrometallurgy, 323 Electroplating, 324 18. Electrochemical Reactors 18.1 18.2 18.3 297 Reacting Metal Electrodes, 297 Anodic Metal Dissolution, 299 Surface-Layer Formation, 301 Passivation of Electrodes, 305 Cathodic Metal Deposition, 310 Electrochemical Metal Treatments, 315 17. Industrial Electrolytic Processes 17.1 17.2 17.3 17.4 261 Design Principles, 327 Separators, 330 Macrokinetics of Electrochemical Processes (Systems with Distributed Parameters), 334 327 ftoc.qxd 10/29/2005 12:01 PM Page ix CONTENTS 18.4 18.5 Porous Electrodes, 337 Three-Dimensional Electrodes, 342 19. Batteries (Electrochemical Power Sources) 19.1 19.2 19.3 19.4 19.5 19.6 369 Electrochemical Capacitors and Supercapacitors, 369 Electrochemical Transducers, 375 22. Corrosion of Metals 22.1 22.2 22.3 361 Introduction, 361 Design Principles of Fuel Cells, 363 Proton-Exchange Membrane Fuel Cells, 364 Direct Methanol Fuel Cells, 366 21. Some Electrochemical Devices 21.1 21.2 343 Chemical Current-Producing Reactions in Batteries, 344 Performance of Batteries, 345 Electrochemical Systems, 349 Primary Batteries, 350 Storage Batteries, 353 Lithium Batteries, 367 20. Fuel Cells 20.1 20.2 20.3 20.4 ix 379 Various Types of Corrosion, 380 Mechanisms of Corrosion Processes, 381 Corrosion Protection, 384 23. Electrochemical Methods of Analysis 387 23.1 Conductometry, 388 23.2 Coulometry, 388 23.3 Amperometry, 389 23.4 Polarography, 390 23.5 Transient Voltammetric Techniques, 394 23.6 Potentiometry, 398 24. Electrochemistry and the Environment Alexander Skundin (Sections 24.1 to 24.4) and Alvin J. Salkind (Section 24.5) 24.1 24.2 24.3 Chemical and Electrochemical Processes, 405 Monitoring the Environment, 406 Purification Procedures (Elimination of Pollutants), 408 405 ftoc.qxd 10/29/2005 x 12:01 PM Page x CONTENTS 24.4 24.5 PART IV Medical Applications of Electrochemistry, 411 Electrochemical Aspects of Bone Remodeling and Fracture Repair, 413 SELECTED TOPICS IN ELECTROCHEMISTRY 25. Solid-State Electrochemistry Ulrich Stimming and Hengyong Tu (Part A) 417 419 Part A. Solid Electrolytes, 419 25.1 Defects in Solids, 419 25.2 Solid Ion Conductors, 425 25.3 Solid Mixed Ionic–Electronic Conductors, 436 25.4 Electrochemical Reactions at Interfaces with Solid Electrolytes, 438 Part B. Solid-State Reactions, 441 25.5 Heterogeneous Solid-State Reactions, 441 25.6 Electrochemical Intercalation, 443 26. Conductive Polymers Klaus Müller 26.1 26.2 26.3 449 Active Polymers, 449 Polymers with Ionic Functions, 450 Polymers with Electronic Functions, 457 27. Physical Methods for Investigation of Electrode Surfaces James McBreen 467 27.1 Topics of Investigation, 468 27.2 X-Ray Methods, 470 27.3 Scanning Probe Methods, 484 27.4 Electrochemical Quartz Crystal Microbalance, 487 27.5 Optical Spectroscopy, 491 27.6 Infrared Spectroscopy, 503 27.7 Electrochemical NMR, 506 27.8 Ex Situ Methods, 507 27.9 The Future of Physical Methods in Electrochemistry, 516 28. Electrocatalysis 28.1 28.2 Introduction, 521 Electrocatalysis and Adsorption Effects, 523 521 ftoc.qxd 10/29/2005 12:01 PM Page xi CONTENTS 28.3 28.4 28.5 28.6 28.7 28.8 28.9 28.10 Metal Electrodes: Influence of the Nature of the Metal, 524 Metal Electrodes: Influence of Surface State and Structure, 530 Highly Disperse Metal Catalysts, 535 Binary and Multicomponent Metal Catalysts, 539 Nonmetallic Catalysts, 542 Stability of Electrocatalysts, 550 Other Aspects of Electrocatalysis, 551 Discussion, 552 29. Photoelectrochemistry 29.1 29.2 29.3 29.4 607 Equilibrium Galvani Potential Difference, 608 Ideally Polarizable ITIES, 612 Polarization Measurements, 612 Structure of ITIES, 614 Charge-Transfer Rate, 616 Applications, 618 33. Various Electrochemical Phenomena Yurij Tolmachev (Section 33.1) and Leonid Kanevsky (Section 33.2) 33.1 33.2 595 Electrokinetic Potential, 597 Basic Equations of Electrokinetic Processes, 600 Practical Use of Electrokinetic Processes, 605 32. Interfaces Between Two Immiscible Electrolyte Solutions Zdeněk Samec 32.1 32.2 32.3 32.4 32.5 32.6 573 Transmission of the Nervous Impulse, 575 Bioenergetics, 584 Electrochemical Methods in Biology and Medicine, 589 31. Electrokinetic Processes 31.1 31.2 31.3 557 Energy Levels of Electrons, 558 Electron Photoemission into Solutions, 562 Photoexcitation of Semiconductor Electrodes, 564 Photoexcitation of Reacting Species, 570 30. Bioelectrochemistry 30.1 30.2 30.3 xi Electrochromism, 621 Electrochemical Noise, 626 621