VOLUME 2B MODERN ELECTROCHEMISTRY SECOND EDITION Electrodics in Chemistry, Engineering, Biology, and Environmental Science

Transcription

1 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/Plenum Publishers New York, Boston, Dordrecht, London, Moscow

2 CONTENTS CHAPTER 10 PHOTOELECTROCHEMISTRY 10.1 Introduction More on Band Bending at the Semiconductor/Solution Interface Introduction Why the Potential Difference in a Semiconductor with No Surface States Is Largely Inside the Solid Phase Bending the Bands Photoexcitation of Electrons by Absorption of Light p-typephotocathodes Then-Type Photoanode The Rate-Determining Step in Photoelectrochemical Reactions The "Schottky Barrier" A Theory of the Photocurrent for Semiconductors of Low Surface State Concentration Near the Limiting Current What Has Been Learned about Photoelectrochemistry So Far? Surface Effects in Photoelectrochemistry Introduction Surface States Introduction Determination of Surface States What Causes a Surface State? The Effect of Surface States on the Distribution of Potential in the Semiconductor Interface 1564 xiii

3 xiv CONTENTS Kinetic Photoelectrochemical Processes at High Surface State Semiconductors Looking Back and Looking Forward at Photoelectrochemistry Photoelectrocatalysis The Photoelectrochemical Splitting of Water The Need for Photoelectrocatalysis Could Cheap Ti0 2 Be Used in the Economic Photoelectrolysis ofwater? The Photoelectrochemical Reduction of CO Photoelectrochemical Waste Removal Retrospect and Prospect for Photoelectrochemistry, Particularly in Respect to the Splitting of Water 1581 Further Reading 1582 Appendix 1. A Brief Note on Electroluminescence and Electroreflectance 1585 Appendix 2. Electrochemical Preparation of Semiconductor Electrodes Appendix 3. High-Resolution Techniques in the Study of Semiconductor Surfaces 1586 CHAPTER 11 SELECTED ASPECTS OF ORGANOELECTROCHEMISTRY Introduction The Modernization of an Ancient Subject The Plus and Minus of Using an Electrochemical Route for Synthesis Determining the Mechanisms of Organoelectrochemical Reactions Introduction Anodic Oxidation of ß-Cyanoethyl Ethers The Manufacture of Nylon Chiral Electrodes Optical Activity at Electrodes Electro-Organic Syntheses Cell Design New Electrode Materials A Moving Frontier Electronically Conducting Organic Polymers Introduction 1612

4 CONTENTS xv Ionically Doped Organic Polymers as Semiconductors General Properties of Electronically Conducting Organic Polymers Status of Polypyrrole Use of Polypyrrole in Electrocatalysis The Oxidation and Polymerization of the Monomer The Structure of the Polypyrrole/Solution Interface Relevant Facts Structure Practical Electrochemical Uses of Electronically Conducting Polymers (see also Section 4.9.2) Electronically Conducting Organic Compounds: Problems and the Future Designer Electrodes Introduction Formation of Monolayers of Organic Molecules on Electrodes Apparent Catalysis by Redox Couples Introduced into Polymers Attached to Electrodes Conclusion 1631 Further Reading 1631 CHAPTER 12 ELECTROCHEMISTRY IN MATERIALS SCIENCE Charge Transfer, Surface, and Civilization Introduction A Corroding Metal Is Analogous to a Short-Circuited Energy-Producing Cell Mechanism of the Corrosion of Ultrapure Metals What Is the Cathodic Reaction in Corrosion? Thermodynamics and the Stability of Metals Potential-pH (or Pourbaix) Diagrams: Uses and Abuses The Corrosion Current and the Corrosion Potential The Basic Electrodics of Corrosion in the Absence of Oxide Films An Understanding of Corrosion in Terms of Evans Diagrams How Corrosion Rates Are Measured Method 1: The Weight-Loss Method Method 2: Electrochemical Approach Impedance Bridge Version of the Stern-Geary Approach Other Methods The Mechanisms of the Corrosion Reactions Involving the Dissolution of Iron Something about the Mechanism of the Anodic Dissolution of Iron

5 xvi CONTENTS The Mechanism of Hydrogen Evolution (HER) on Iron (A Cathodic Partner Reaction in Corrosion often Met in Acid Solution) The Mechanism of Oxygen Reduction on Iron Where We Are Now: Looking Back at the Beginning Some Common Examples of Corrosion 1674 Further Reading Inhibiting Corrosion Introduction Cathodic and Anodic Protection Corrosion Inhibition by the Addition of Substances to the Electrolytic Environment of a Corroding Metal Corrosion Prevention by Charging the Corroding Metal with Electrons from an External Source Anodic Protection Organic Inhibition: the Fuller Story Relations between the Structure of the Organic Molecule and Its Ability to Inhibit Corrosion Toward a Designer Inhibitor Polymer Films as an Aspect of Corrosion Inhibition Nature of the Metal Surface in Corrosion Inhibition Green Inhibitors Looking Back on Some Methods by Which We Are Able to Inhibit Corrosion 1705 Further Reading The Protection of Aluminum by Transition Metal Additions Introduction Some Facts Relevant to the Transition Metal Effect on Inhibiting Al Corrosion The Model by Which Tiny Concentrations of Transition Metal Ions Retard Corrosion of Al Passivation Introduction Some Definitions The Nature of the Passive Layer Structure of the Passive Film Depassivation Effects of Marine Organisms on Passive Layers Localized Corrosion Introduction The Initiation Mechanisms Forming a Pit or Crevice A Clamp on a Plain Piece of Metal Pits in Stainless Steel 1730

6 CONTENTS xvii Events in Pits Modeling 1731 Further Reading Electrochemical Aspects of the Effect of Hydrogen on Metal Hydrogen Diffusion into a Metal The Preferential Diffusion of Absorbed Hydrogen to Regions of Stress in a Metal Hydrogen Can Crack Open a Metal Surface Surface Instability and the Internal Decay of Metals: Stress-Corrosion Cracking Practical Consequences of Stress-Corrosion Cracking Surface Instability and Internal Decay of Metals: Hydrogen Embrittlement What is the Direct Experimental Evidence for Very High Pressures in Voids in Metals? Introduction A Partial Experimental Verification of High Pressures in Metal Voids Indirect Measurement of High Pressures in Voids Damage Caused Internally in Metals by the Presence of H (and H 2 ) at Varying Overpotentials 1759 Further Reading Fatigue The Preferential Flotation of Minerals: An Application of the Mixed Potential Concept Description At the Cutting Edge of Corrosion Research: The Use of STM and ATM Application A Laser-Based Technique for the Quantitative Measurement of H in Local Areas Description Other Methods of Examining Local Corrosion Description 1771 Further Reading A Bird's Eye View of Corrosion Description 1772 Further Reading 1775

7 xviii CONTENTS CHAPTER 13 CONVERSION AND STORAGE OF ELECTROCHEMICAL ENERGY Introduction A Brief History of Fuel Cells Efficiency Maximum Intrinsic Efficiency in Electrochemical Conversion of the Energy of a Chemical Reaction to Electric Energy Actual Efficiency of an Electrochemical Energy Converter Physical Interpretation of the Absence of the Carnot Efficiency Factor in Electrochemical Energy Conversion Cold Combustion Kinetics of Fuel Cell Reactions Making V near V e Is the Central Problem of Electrochemical Energy Conversion Electrochemical Parameteis That Must Be Optimized for Good Energy Conversion The Power Output of an Electrochemical Energy Converter The Electrochemical Engine Electrodes Burning Oxygen from Air Porous Electrode Special Configurations of Electrodes in Electrochemical Energy Converters Types of Fuel Cells What Is Known So Far about Fuel Cells Electrochemical Energy Converters General Aspects of the Practical Fuel Cells The Cells Efficiency of Energy Conversion and the Tafel Equation Alkaline Fuel Cells Phosphoric Acid Fuel Cells High-Temperature Fuel Cells Solid Polymer Electrolyte Fuel Cell Electrochemical Engines for Vehicular Transportation The Electrochemical Engine The Re-former Development of the Proton-Exchange Membrane Fuel Cell for Use in Automotive Transportation General 1830

8 CONTENTS xix Fundamental Research that Underlay Development of this Cell The Electric Car Schematic A Chord of Continuity Hybrids Involving Fuel Cells, Batteries, etc Direct MeOH Fuel Cells General Development of a Fuel Cell-Based Technology Fuel Cell Power Plants Household Energy Vehicular Transportation Railways Seagoing Vessels Aircraft Industry Space The Second Fuel Cell Principle Midway: The Need to Reduce Massive C0 2 Emissions from Man-Made Sources Fuel Cells: The Summary 1846 Further Reading Electrochemical Energy Storage Introduction A Few Highlights in the Development of Batteries History Properties of Electrochemical Energy Storers The Discharge Plot The Ragone Plot Measures of Battery Performance Charging and Discharging a Battery Some Individual Batteries Introduction Classical Batteries Lead-Acid Nickel-Cadmium Zinc-Manganese Dioxide Modern Batteries Zinc-Air Nickel-Metal Hydride Li Some Batteries for Special Purposes 1877

9 xx CONTENTS The View Ahead with Batteries General Electrochemical Capacitors as Energy Storers Introduction Can the Energy Storage Possibilities with Electrochemical Condensers be Greatly Increased? Projected Uses of Electrochemical Capacitors Batteries: An Overview 1886 Further Reading 1888 CHAPTER 14 BIOELECTROCHEMISTRY Bioelectrodics Introduction Useful Preliminaries Size Why Should Electrochemists Be Interested in Amino Acids, Proteins, and DNA? Cells, Membranes, and Mitochondria Membrane Potentials Preliminary Simplistic Theories of Membrane Potentials Modern Approaches to the Theory of Membrane Potentials Electrical Conduction in Biological Organisms Electronic Protonic The Electrochemical Mechanisms of the Nervous System: An Unfinished Section General Facts The Rise and Fall of the Theory of the Spike Potential Interfacial Electron Transfer in Biological Systems Introduction Adsorption of Proteins onto Metals from Solution Electron Transfer from Modified Metals to Dissolved Protein in Solution Electron Transfer from Biomaterials to Simple Redox Ions in Solution

10 CONTENTS xxi Theoretical Aspects of Electron Transfer from Solid Proteins to Ions in Solution Conduction and Electron Transfer in Biological Systems: Retrospect and Prospect 1944 Further Reading Electrochemical Communication in Biological Organisms Introduction Chemical Signaling Electrical Signaling Introduction Sensitivity of Biological Organisms to Minute Electric Field Strengths Signaling Carcinogenesis Enzymes as Electrodes Preliminary What Are Enzymes? Electrodes Carrying Enzymes The Electrochemical Enzyme-Catalyzed Oxidation of Styrene Metabolism An Abnormally Efficient Process of Energy Conversion Williams Model Development of the Fuel Cell Model in Biological Energy Conversion Distribution and Storage Electrochemical Aspects of Some Bioprocesses Introduction Superoxide as a Pretoxin Cardiovascular Diseases The Effects of Electromagnetic Radiation on Biological Organisms Microbial Effects Bactericidal Fuel-Cell Related Electrochemical Growth of Bones and Related Phenomena Electroanalgesia Other Effects Monitoring Neurotransmitters in the Intact Brain and Other Single- Cell Studies Introduction Summary: Medical Effects, Brain, and Single-Cell Experiments Further Reading 1980

11 xxii CONTENTS CHAPTER 15 ENVIRONMENTALLY ORIENTED ELECTROCHEMISTRY The Environmental Situation The Electrochemical Advantage Global Warming Facts The Solar-Hydrogen Solution The Ideas The Electrochemistry of Water Splitting The Electrolysis of Sea Water Superelectrolyzers Photoelectrochemical Splitting of Water Large-Scale Solar-Hydrogen Production Solar-Hydrogen Farms The Electrochemical Transport System Introduction Electrochemically Powered Cars The Fuel Cell The Fixing of C Introduction The Possible Reduction Product Reduction of C0 2 on Metals The Mechanism of C0 2 Reduction Photoelectrochemical Reduction of C Conversion of an Organic Compound in Photoelectrochemical Fixing Prospects in the Electrochemical Reduction of C Removal of Wastes Introduction Waste Water SulfurDioxide Removal of Metals: Aquifers The Destruction of Nitrates Electrochemical Treatment of Low-Level, Nuclear Wastes Mediator-Aided Destruction of Organic Wastes (Particularly Toxic, Organic Waste) Bactericidal Effects The Special Problem of H 2 S Introduction Electrochemical Decomposition of H 2 S 2031

12 CONTENTS xxiii Photoelectrochemical Decomposition of H 2 S Electrochemical Sewage Disposal Electrochemical Decontamination of Soil Introduction The Mechanism Experimental Work Summary on Soil Remediation Retrospect and Prospect A Parting Word 2039 Further Reading 2042 Index xxv >