Understanding Voltammetry (2nd Edition) / Edition 2

The power of electrochemical measurements in respect of thermodynamics, kinetics and analysis is widely recognized but the subject can be unpredictable to the novice even if they have a strong physical and chemical background, especially if they wish to pursue the study of quantitative measurements further. Accordingly, some significant experiments are perhaps wisely never attempted while the literature is sadly replete with flawed attempts at rigorous voltammetry.

This textbook considers how to go about designing, explaining and interpreting experiments centered around various forms of voltammetry (cyclic, microelectrode, hydrodynamic, etc.). The reader is assumed to have attained a knowledge equivalent to Masters level of physical chemistry but no exposure to electrochemistry in general, or voltammetry in particular. While the book is designed to “”stand alone””, references to important research papers are given to provide aft introductory entry into the literature.

In comparison to the first edition, two new chapters – transport via migration and nanoelectrochemistry – are added. Minor changes and updates are also made throughout the textbook to facilitate enhanced understanding and greater clarity of exposition

Table Of Contents:

Preface vii

1 Equilibrium Electrochemistry and the Nernst Equation 1

1.1 Chemical Equilibrium 1

1.2 Electrochemical Equilibrium: Introduction 5

1.3 Electrochemical Equilibrium: Electron Transfer at the Solution-Electrode Interface 9

1.4 Electrochemical Equilibrium: The Nernst Equation 11

1.5 Walther Hermann Nernst 17

1.6 Reference Electrodes and the Measurement of Electrode Potentials 19

1.7 The Hydrogen Electrode as a Reference Electrode 26

1.8 Standard Electrode Potentials and Formal Potentials 27

1.9 Formal Potentials and Experimental Voltammetry 30

1.10 Electrode Processes: Kinetics vs. Thermodynamics 32

2 Electrode Kinetics 35

2.1 Currents and Reaction Fluxes 35

2.2 Studying Electrode Kinetics Requires Three Electrodes 37

2.3 Butler-Volmer Kinetics 40

2.4 Standard Electrochemical Rate Constants and Formal Potentials 43

2.5 The Need for Supporting Electrolyte 45

2.6 The Tafel Law 46

2.7 Julius Tafel 47

2.8 Multistep Electron Transfer Processes 49

2.9 Tafel Analysis and the Hydrogen Evolution Reaction 52

2.10 B. Stanley Pons 57

2.11 Cold Fusion-The Musical! 58

2.12 Why Are Some Standard Electrochemical Rate Constants Large but Others Slow? The Marcus Theory of Electron Transfer: An Introduction 60

2.13 Marcus Theory: Taking it Further. Inner and Outer Sphere Electron Transfer 66

2.14 Marcus Theory: Taking it Further. Adiabatic and Non-Adiabatic Reactions 67

2.15 Marcus Theory: Taking it Further. Calculating the Gibbs Energy of Activation 70

2.16 Relationship between Marcus Theory and Butler-Volmer Kinetics 73

2.17 Marcus Theory and Experiment. Success! 74

3 Diffusion 77

3.1 Ficks 1st Law of Diffusion 77

3.2 Ficks 2nd Law of Diffusion 79

3.3 The Molecular Basis of Ficks Laws 81

3.4 How Did Fick Discover His Laws? 83

3.5 The Cottrell Equation: Solving Ficks 2nd Law 88

3.6 The Cottrell Problem: The Case of Unequal Diffusion Coefficients 92

3.7 The Nernst Diffusion Layer 94

3.8 Mass Transfer vs. Electrode Kinetics: Steady-State Current-Voltage Waveshapes 97

3.9 Mass Transport Corrected Tafel Relationships 100

4 Cyclic Voltammetry at Macroelectrodes 107

4.1 Cyclic Voltammetry: The Experiment 107

4.2 Cyclic Voltammetry: Solving the Transport Equations 109

4.3 Cyclic Voltammetry: Reversible and Irreversible Kinetics 111

4.4 What Dictates Reversible and Irreversible Behaviour? 119

4.5 Reversible and Irreversible Behaviour: The Effect of Voltage Scan Rate 120

4.6 Reversible versus Irreversible Voltammetry: A Summary 126

4.7 The Measurement of Cyclic Voltammograms: Th