VOLUME 2B MODERN ELECTROCHEMISTRY SECOND EDITION Electrodics in Chemistry, Engineering, Biology, and Environmental Science
Total Page:16
File Type:pdf, Size:1020Kb
VOLUME 2B MODERN ELECTROCHEMISTRY SECOND EDITION Electrodics in Chemistry, Engineering, Biology, and Environmental Science This page intentionally left blank VOLUME 2B MODERN ELECTROCHEMISTRY SECOND EDITION Electrodics in Chemistry, Engineering, Biology, and Environmental Science John O'M Bockris Molecular Green Technology College Station, Texas and Amulya K. N. Reddy President International Energy Initiative Bangalore, India KLUWER ACADEMIC PUBLISHERS NEW YORK, BOSTON, DORDRECHT, LONDON, MOSCOW eBook ISBN: 0-306-48036-0 Print ISBN: 0-306-46324-5 ©2004 Kluwer Academic Publishers New York, Boston, Dordrecht, London, Moscow Print ©2000 Kluwer Academic/Plenum Publishers New York All rights reserved No part of this eBook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher Created in the United States of America Visit Kluwer Online at: http://kluweronline.com and Kluwer's eBookstore at: http://ebooks.kluweronline.com To Tom Bacon This page intentionally left blank PREFACE TO THE FIRST EDITION This book had its nucleus in some lectures given by one of us (J.O’M.B.) in a course on electrochemistry to students of energy conversion at the University of Pennsylva- nia. It was there that he met a number of people trained in chemistry, physics, biology, metallurgy, and materials science, all of whom wanted to know something about electrochemistry. The concept of writing a book about electrochemistry which could be understood by people with very varied backgrounds was thereby engendered. The lectures were recorded and written up by Dr. Klaus Muller as a 293-page manuscript. At a later stage, A.K.N.R. joined the effort; it was decided to make a fresh start and to write a much more comprehensive text. Of methods for direct energy conversion, the electrochemical one is the most advanced and seems the most likely to become of considerable practical importance. Thus, conversion to electrochemically powered transportation systems appears to be an important step by means of which the difficulties of air pollution and the effects of an increasing concentration in the atmosphere of carbon dioxide may be met. Corro- sion is recognized as having an electrochemical basis. The synthesis of nylon now contains an important electrochemical stage. Some central biological mechanisms have been shown to take place by means of electrochemical reactions. A number of American organizations have recently recommended greatly increased activity in training and research in electrochemistry at universities in the United States. Three new international journals of fundamental electrochemical research were established between 1955 and 1965. In contrast to this, physical chemists in U.S. universities seem—perhaps partly because of the absence of a modern textbook in English—out of touch with the revolution in fundamental interfacial electrochemistry which has occurred since 1950. The fragments of electrochemistry which are taught in many U.S. universities belong not to the space age of electrochemically powered vehicles, but to the age of vii viii PREFACE TO THE FIRST EDITION thermodynamics and the horseless carriage; they often consist of Nernst’s theory of galvanic cells (1891) together with the theory of Debye and Hückel (1923). Electrochemistry at present needs several kinds of books. For example, it needs a textbook in which the whole field is discussed at a strong theoretical level. The most pressing need, however, is for a book which outlines the field at a level which can be understood by people entering it from different disciplines who have no previous background in the field but who wish to use modern electrochemical concepts and ideas as a basis for their own work. It is this need which the authors have tried to meet. The book’s aims determine its priorities. In order, these are: 1. Lucidity. The authors have found students who understand advanced courses in quantum mechanics but find difficulty in comprehending a field at whose center lies the quantum mechanics of electron transitions across interfaces. The difficulty is associated, perhaps, with the interdisciplinary character of the material: a background knowledge of physical chemistry is not enough. Material has therefore sometimes been presented in several ways and occasionally the same explanations are repeated in different parts of the book. The language has been made informal and highly explanatory. It retains, sometimes, the lecture style. In this respect, the authors have been influenced by The Feynman Lectures on Physics. 2. Honesty. The authors have suffered much themselves from books in which proofs and presentations are not complete. An attempt has been made to include most of the necessary material. Appendices have been often used for the presentation of mathematical derivations which would obtrude too much in the text. 3. Modernity. There developed during the 1950’s a great change in emphasis in electrochemistry away from a subject which dealt largely with solutions to one in which the treatment at a molecular level of charge transfer across interfaces dominates. This is the "new electrochemistry," the essentials of which, at an elementary level, the authors have tried to present. 4. Sharp variation is standard. The objective of the authors has been to begin each chapter at a very simple level and to increase the level to one which allows a connecting up to the standard of the specialized monograph. The standard at which subjects are presented has been intentionally variable, depending particularly on the degree to which knowledge of the material appears to be widespread. 5. One theory per phenomenon. The authors intend a teaching book, which acts as an introduction to graduate studies. They have tried to present, with due admission of the existing imperfections, a simple version of that model which seemed to them at the time of writing to reproduce the facts most consistently. They have for the most part refrained from presenting the detailed pros and cons of competing models in areas in which the theory is still quite mobile. In respect to references and further reading: no detailed references to the literature have been presented, in view of the elementary character of the book’s contents, and the corresponding fact that it is an introductory book, largely for beginners. In the PREFACE TO THE FIRST EDITION ix "further reading" lists, the policy is to cite papers which are classics in the development of the subject, together with papers of particular interest concerning recent develop- ments, and in particular, reviews of the last few years. It is hoped that this book will not only be useful to those who wish to work with modern electrochemical ideas in chemistry, physics, biology, materials science, etc., but also to those who wish to begin research on electron transfer at interfaces and associated topics. The book was written mainly at the Electrochemistry Laboratory in the University of Pennsylvania, and partly at the Indian Institute of Science in Bangalore. Students in the Electrochemistry Laboratory at the University of Pennsylvania were kind enough to give guidance frequently on how they reacted to the clarity of sections written in various experimental styles and approaches. For the last four years, the evolving versions of sections of the book have been used as a partial basis for undergraduate, and some graduate, lectures in electrochemistry in the Chemistry Department of the University. The authors' acknowledgment and thanks must go first to Mr. Ernst Cohn of the National Aeronautics and Space Administration. Without his frequent stimulation, including very frank expressions of criticism, the book might well never have emerged from the Electrochemistry Laboratory. Thereafter, thanks must go to Professor B. E. Conway, University of Ottawa, who gave several weeks of his time to making a detailed review of the material. Plentiful help in editing chapters and effecting revisions designed by the authors was given by the following: Chapters IV and V, Dr. H. Wroblowa (Pennsylvania); Chapter VI, Dr. C. Solomons (Pennsylvania) and Dr. T. Emi (Hokkaido); Chapter VII, Dr. E. Gileadi (Tel-Aviv); Chapters VIII and IX, Prof. A. Despic (Belgrade), Dr. H. Wroblowa, and Mr. J. Diggle (Pennsylvania); Chapter X, Mr. J. Diggle; Chapter XI, Dr. D. Cipris (Pennsylvania). Dr. H. Wroblowa has to be particularly thanked for essential contributions to the composition of the Appendix on the measurement of Volta potential differences. Constructive reactions to the text were given by Messers. G. Razumney, B. Rubin, and G. Stoner of the Electrochemistry Laboratory. Advice was often sought and accepted from Dr. B. Chandrasekaran (Pennsylvania), Dr. S. Srinivasan (New York), and Mr. R. Rangarajan (Bangalore). Comments on late drafts of chapters were made by a number of the authors' colleagues, particularly Dr. W. McCoy (Office of Saline Water), Chapter II; Prof. R. M. Fuoss (Yale), Chapter III; Prof. R. Stokes (Armidale), Chapter IV; Dr. R. Parsons (Bristol), Chapter VII; Prof. A. N. Frumkin (Moscow), Chapter VIII; Dr. H. Wrob- lowa, Chapter X; Prof. R. Staehle (Ohio State), Chapter XI. One of the authors (A.K.N.R.) wishes to acknowledge his gratitude to the authorities of the Council of Scientific and Industrial Research, India, and the Indian Institute of Science, Banga- lore, India, for various facilities, not the least of which were extended leaves of absence. He wishes also to thank his wife and