Professor Noam Eliaz is a full professor, Director of the Biomaterials and Corrosion Laboratory, and the founder of the Department of Materials Science and Engineering at TAU. He earned a BSc degree in Materials Engineering, an MBA degree, and a PhD degree (direct track) in Materials Engineering, all cum laude from Ben-Gurion University of the Negev. Prior to joining TAU, he was a Fulbright and Rothschild Fellow at MIT. His research is interdisciplinary and includes electrodeposition of calcium phosphate coatings for implants, electrodeposition of special alloys for high-temperature applications, corrosion, and failure analysis. From 2005 to 2017 he was the Editor-in-Chief of the journal Corrosion Reviews, and currently he is an editorial board member of this journal as well as of Current Topics in Electrochemistry, Corrosion, and Materials Degradation, and Bioceramics Development and Applications. He is an elected member of The Israel Young Academy and was appointed to the Governing Board of The German-Israeli Foundation for Scientific Research and Development (GIF). He has won numerous awards, including NACE International's Herbert H. Uhlig Award (2010), Fellow Award (2012), and Technical Achievement Award (2014), as well as Fellow of The Japanese Society for the Promotion of Science (2005?2007) and the T.P. Hoar Award (2003).

Eliezer Gileadi has been a Professor of Chemistry at Tel-Aviv University (TAU) since 1966 (Emeritus since 2000). He obtained his [...]. at the Hebrew University in Jerusalem and his Ph.D. at the University of Ottawa, Canada. He has been a visiting professor and a lecturer at many institutes worldwide, including the University of Virginia, The University of Pennsylvania, Case Western Reserve University, The Johns Hopkins University, University of Ottawa, etc. He is a Fellow of the Royal Society of Canada, the Electrochemical Society, the American Association for the Advancement of Science, and the International Society for Electrochemistry. He received from the Electrochemical Society the prestigious Olin-Palladium Award and the Henry B. Linford Award for Distinguished Teaching. He taught this subject for 40 years and consulted to industry.

Preface xvii

Symbols and Abbreviations xix

1 Introduction 1

1.1 General Considerations 1

1.1.1 The Transition from Electronic to Ionic Conduction 1

1.1.2 The Resistance of the Interface can be Infinite 2

1.1.3 Mass-Transport Limitation 2

1.1.4 The Capacitance at the Metal/Solution Interphase 4

1.2 Polarizable and Nonpolarizable Interfaces 4

1.2.1 Phenomenology 4

1.2.2 The Equivalent Circuit Representation 5

Further Reading 7

2 The Potentials of Phases 9

2.1 The Driving Force 9

2.1.1 Definition of the Electrochemical Potential 9

2.1.2 Separability of the Chemical and the Electrical Terms 10

2.2 Two Cases of Special Interest 11

2.2.1 Equilibrium of a Species Between two Phases in Contact 11

2.2.2 Two Identical Phases not at Equilibrium 12

2.3 The Meaning of the Standard Hydrogen Electrode (SHE) Scale 13

Further Reading 15

3 Fundamental Measurements in Electrochemistry 17

3.1 Measurement of Current and Potential 17

3.1.1 The Cell Voltage is the Sum of Several Potential Differences 17

3.1.2 Use of a Nonpolarizable Counter Electrode 17

3.1.3 The Three-Electrode Setup 18

3.1.4 Residual jRS Potential Drop in aThree-Electrode Cell 18

3.2 Cell Geometry and the Choice of the Reference Electrode 19

3.2.1 Types of Reference Electrodes 19

3.2.2 Use of an Auxiliary Reference Electrode for the Study of Fast Transients 20

3.2.3 Calculating the Uncompensated Solution Resistance for a few Simple Geometries 21

3.2.3.1 Planar Configuration 21

3.2.3.2 Cylindrical Configuration 21

3.2.3.3 Spherical Symmetry 22

3.2.4 Positioning the Reference Electrode 22

3.2.5 Edge Effects 24

Further Reading 26

4 Electrode Kinetics: Some Basic Concepts 27

4.1 Relating Electrode Kinetics to Chemical Kinetics 27

4.1.1 The Relation of Current Density to Reaction Rate 27

4.1.2 The Relation of Potential to Energy of Activation 28

4.1.3 Mass-Transport Limitation Versus Charge-Transfer Limitation 30

4.1.4 The Thickness of the Nernst Diffusion Layer 31

4.2 Methods of Measurement 33

4.2.1 Potential Control Versus Current Control 33

4.2.2 The Need to Measure Fast Transients 35

4.2.3 Polarography and the Dropping Mercury Electrode (DME) 37

4.3 Rotating Electrodes 40

4.3.1 The Rotating Disk Electrode (RDE) 40

4.3.2 The Rotating Cone Electrode (RConeE) 44

4.3.3 The Rotating Ring Disk Electrode (RRDE) 45

Further Reading 47

5 Single-Step Electrode Reactions 49

5.1 The Overpotential, ;; 49

5.1.1 Definition and Physical Meaning of Overpotential 49

5.1.2 Types of Overpotential 51

5.2 Fundamental Equations of Electrode Kinetics 52

5.2.1 The Empirical Tafel Equation 52

5.2.2 The Transition-State Theory 53

5.2.3 The Equation for a Single-Step Electrode Reaction 54

5.2.4 Limiting Cases of the General Equation 56

5.3 The Symmetry Factor, ;;, in Electrode Kinetics 59

5.3.1 The Definition of ;; 59

5.3.2 The Numerical Value of ;; 60

5.4 The Marcus Theory of Charge Transfer 61

5.4.1 Outer-Sphere Electron Transfer 61

5.4.2 The Born-Oppenheimer Approximation 62

5.4.3 The Calculated Energy of Activation 63

5.4.4 The Value of ;; and its Potential Dependence 64

5.5 Inner-Sphere Charge Transfer 65

5.5.1 Metal Deposition 65

Further Reading 66

6 Multistep Electrode Reactions 67

6.1 Mechanistic Criteria 67

6.1.1 The Transfer Coefficient, ;;, and its Relation to the Symmetry Factor, ;; 67

6.1.2 Steady State and Quasi-Equilibrium 69

6.1.3 Calculation of the Tafel Slope 71

6.1.4 Reaction Orders in Electrode Kinetics 74

6.1.5 The Effect of pH on Reaction Rates 77

6.1.6 The Enthalpy of Activation 79

Further Reading 81

7 Specific Examples of Multistep Electrode Reactions 83

7.1 Experimental Considerations 83

7.1.1 Multiple Processes in Parallel 83

7.1.2 The Level of Impurity that can be Tolerated 84

7.2 The Hydrogen Evolution Reaction (HER) 87

7.2.1 Hydrogen Evolution on Mercury 87

7.2.2 Hydrogen Evolution on Platinum 89

7.3 Possible Paths for the Oxygen Evolution Reaction 91

7.4 The Role and Stability of Adsorbed Intermediates 94

7.5 Adsorption Energy and Catalytic Activity 95

Further Reading 96

8 The Electrical Double Layer (EDL) 97

8.1 Models of Structure of the EDL 97

8.1.1 Phenomenology 97

8.1.2 The Parallel-Plate Model of Helmholtz 99

8.1.3 The Diffuse Double Layer Model of Gouy and Chapman 100

8.1.4 The Stern Model 103

8.1.5 The Role of the Solvent at the Interphase 105

Further Reading 107

9 Electrocapillary 109

9.1 Thermodynamics 109

9.1.1 Adsorption and Surface Excess 109

9.1.2 The Gibbs Adsorption Isotherm 111

9.1.3 The Electrocapillary Equation 112

9.2 Methods of Measurement and Some Results 114

9.2.1 The Electrocapillary Electrometer 114

9.2.2 Some Experimental Results 119

9.2.2.1 The Adsorption of Ions 119

9.2.2.2 Adsorption of NeutralMolecules 120

Further Reading 122

10 Intermediates in Electrode Reactions 123

10.1 Adsorption Isotherms for Intermediates Formed by Charge Transfer 123

10.1.1 General 123

10.1.2 The Langmuir Isotherm and its Limitations 123

10.1.3 Application of the Langmuir Isotherm for Charge-Transfer Processes 125

10.1.4 The Frumkin Adsorption Isotherms 126

10.2 The Adsorption Pseudocapacitance C 127

10.2.1 Formal Definition of C and its Physical Understanding 127

10.2.2 The Equivalent-Circuit Representation 129

10.2.3 Calculation of C as a function of ;; and E 130

Further Reading 133

11 Underpotential Deposition and Single-Crystal Electrochemistry 135

11.1 Underpotential Deposition (UPD) 135

11.1.1 Definition and Phenomenology 135

11.1.2 UPD on Single Crystals 139

11.1.3 Underpotential Deposition of Atomic Oxygen and Hydrogen 141

Further Reading 142

12 Electrosorption 145

12.1 Phenomenology 145

12.1.1 What is Electrosorption? 145

12.1.2 Electrosorption of Neutral Organic Molecules 147

12.1.3 The Potential of Zero Charge, Epzc, and its Importance in Electrosorption 148

12.1.4 TheWork Function and the Potential of Zero Charge 151

12.2 Adsorption Isotherms for Neutral Species 152

12.2.1 General Comments 152

12.2.2 The Parallel-Plate Model of Frumkin et al. 153

12.2.3 The Water Replacement Model of Bockris et al. 155

Further Reading 157

13 Fast Transients, the Time-Dependent Diffusion Equation,and Microelectrodes 159

13.1 The Need for Fast Transients 159

13.1.1 General 159

13.1.2 Small-Amplitude Transients 161

13.1.3 The Sluggish Response of the Electrochemical Interphase 162

13.1.4 How can the Slow Response of the Interphase be Overcome? 162

13.1.4.1 Galvanostatic Transients 162

13.1.4.2 The Double-Pulse GalvanostaticMethod 163

13.1.4.3 The Coulostatic (Charge-Injection) Method 164

13.2 The Diffusion Equation 167

13.2.1 The Boundary Conditions of the Diffusion Equation 167

13.2.1.1 Potential Step, Reversible Case (Chrono-Amperometry) 168

13.2.1.2 Potential Step, High Overpotential Region (Chrono-Amperometry) 171

13.2.1.3 Current Step (Chronopotentiometry) 172

13.3 Microelectrodes 174

13.3.1 The Unique Features of Microelectrodes 174

13.3.2 Enhancement of Diffusion at a Microelectrode 175

13.3.3 Reduction of the Solution Resistance 176

13.3.4 The Choice between Single Microelectrodes and Large Ensembles 176

Further Reading 178

14 Linear Potential Sweep and Cyclic Voltammetry 181

14.1 Three Types of Linear Potential Sweep 181

14.1.1 Very Slow Sweeps 181

14.1.2 Studies of Oxidation or Reduction of Species in the Bulk of the Solution 182

14.1.3 Studies of Oxidation or Reduction of Species Adsorbed on the Surface 182

14.1.4 Double-Layer Charging Currents 183

14.1.5 The Form of the Current-Potential Relationship 185

14.2 Solution of the Diffusion Equations 186

14.2.1 The Reversible Region 186

14.2.2 The High-Overpotential Region 187

14.3 Uses and Limitations of the Linear Potential Sweep Method 188

14.4 Cyclic Voltammetry for Monolayer Adsorption 190

14.4.1 Reversible Region 190

14.4.2 The High-Overpotential Region 192

Further Reading 193

15 Electrochemical Impedance Spectroscopy (EIS) 195

15.1 Introduction 195

15.2 Graphical Representations 200

15.3 The Effect of Diffusion Limitation -TheWarburg Impedance 203

15.4 Advantages, Disadvantages, and Applications of EIS 206

Further Reading 211

16 The Electrochemical Quartz Crystal Microbalance (EQCM) 213

16.1 Fundamental Properties of the EQCM 213

16.1.1 Introduction 213

16.1.2 The EQCM 214

16.1.3 The Effect of Viscosity 217

16.1.4 Immersion in a Liquid 218

16.1.5 Scales of Roughness 218

16.2 Impedance Analysis of the EQCM 219

16.2.1 The Extended Equation for the Frequency Shift 219

16.2.2 Other Factors Influencing the Frequency Shift 220

16.3 Uses of the EQCM as a Microsensor 220

16.3.1 Advantages and Limitations 220

16.3.2 Some Applications of the EQCM 222

Further Reading 225