Understanding Voltammetry:

by Compton, Richard G.; Batchelor-mcauley, Christopher; Dickinson, Edmund J. F.

• ISBN13: 9781848167308
• ISBN10: 184816730X
• Format: Hardcover
• Copyright: 2011-12-31
• Publisher: Imperial College Pr

Summary

The field of electrochemical measurement, with respect to thermodynamics, kinetics and analysis, is widely recognised 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 quantitative measurements. Accordingly, some significant experiments are, perhaps wisely, never attempted, while the literature is sadly replete with flawed attempts at rigorous voltammetry.This book presents problems and worked solutions for a wide range of theoretical and experimental subjects in the field of voltammetry. The reader is assumed to have knowledge up to a Master's level of physical chemistry, but no exposure to electrochemistry in general, or voltammetry in particular, is required. The problems included range in difficulty from senior undergraduate to research level, and develop important practical approaches in voltammetry.The problems presented in the earlier chapters focus on the fundamental theories of thermodynamics, electron transfer and diffusion. Voltammetric experiments and their analysis are then considered, including extensive problems on both macroelectrode and microelectrode voltammetry. Convection, hydrodynamic electrodes, homogeneous kinetics, adsorption and electroanalytical applications are discussed in the later chapters, as well as problems on two rapidly developing fields of voltammetry: weakly supported media and nanoscale electrodes.There is huge interest in the experimental procedure of voltammetry at present, and yet no dedicated question and answer book with exclusive voltammetric focus exists, in spite of the inherent challenges of the subject. This book aims to fill that niche.

Table of Contents

Publisher's Foreword	p. v
Glossary of Symbols and Abbreviations	p. xiii
Equilibrium Electrochemistry and the Nernst Equation	p. 1
Cell Thermodynamics	p. 1
The Nernst Equation	p. 2
The Nernst Equation	p. 3
The Nernst Equation	p. 5
Theory of the Nernst Equation	p. 5
The Debye-Hückel Limiting Law	p. 7
Cell Reaction and Equilibrium Constant	p. 10
Cell Reaction and Equilibrium Constant	p. 11
Cell Reaction and Solubility Product	p. 12
Cell Reaction and pKa	p. 13
Cell Thermodynamics and Temperature	p. 14
Cell Thermodynamics and Temperature	p. 15
Cell Energetics	p. 16
Cell EMF and pH	p. 17
Cell Reaction and Equilibria	p. 18
Cell Reaction and Kw	p. 19
Cell Reaction and Disproportionation	p. 20
Fuel Cell Energetics	p. 21
Fuel Cell Energetics	p. 22
The Influence of Temperature on the Self-Ionisation of Water	p. 23
Cell Reaction and Complexation	p. 24
Reference Electrodes	p. 26
Formal Potentials	p. 27
Formal Potentials	p. 28
Standard Potentials and pH	p. 29
Standard Potentials and pH	p. 30
Standard Potentials and pH	p. 31
Electrode Kinetics	p. 35
Faraday's Laws of Electrolysis	p. 35
Electrodeposition	p. 36
Tafel Analysis: One-Electron Processes	p. 39
Tafel Analysis: Electrochemically Reversible Processes	p. 39
Tafel Analysis: Mass Transport Correction	p. 41
Tafel Analysis: Two-Electron Processes	p. 42
The Butler-Volmer Equation and the Nernst Equation	p. 45
The Hydrogen Evolution Reaction	p. 46
Requirement for Supporting Electrolyte	p. 47
Frumkin Corrections	p. 49
Marcus Theory and Standard Electrochemical Rate Constants	p. 51
Marcus Theory and Butler-Volmer Kinetics	p. 52
Marcus Theory and the Role of Solvent	p. 54
Marcus Theory and the Inverted Region	p. 55
Diffusion	p. 57
Fick's Laws of Diffusion	p. 57
Fick's Laws of Diffusion	p. 58
Diffusion Distances	p. 59
The Cottrell Equation	p. 60
Derivation of the Cottrell Equation	p. 62
Diffusion and Root-Mean-Square Displacement	p. 66
Cyclic Voltammetry at Macroelectrodes	p. 67
Cyclic Voltammetry: Electrochemically Reversible Voltammetry	p. 67
Cyclic Voltammetry: Electrochemically Irreversible Voltammetry	p. 69
Reversible vs Irreversible Voltammetry	p. 71
Voltammetric Diagnostics	p. 72
Voltammetry and Scan Rate Effects	p. 73
Ferrocene Voltammetry	p. 75
Ferrocene Voltammetry	p. 75
Features of Cyclic Voltammograms	p. 76
Derivation of the Randles-Sevcík Equation	p. 77
Reversible Two-Electron Transfer	p. 81
The Influence of pH on Cyclic Voltammetry	p. 82
The Scheme of Squares	p. 84
The EE-Comproportionation Mechanism	p. 86
Voltammetry at Microelectrodes	p. 91
Steady-State Concentration Profile in Spherical Space	p. 91
Current Transients at a Spherical Electrode	p. 93
Linear vs Convergent Diffusion	p. 94
Dissolution of Microparticles	p. 95
Steady-State Limiting Current at a Microdisc	p. 97
Microdisc vs Planar Electrode	p. 98
The Shoup-Szabo Equation	p. 98
Steady-State Electrolysis	p. 100
Effect of Unequal Diffusion Coefficients	p. 101
Temperature Effects on Steady-State Currents	p. 101
ECE Mechanism at a Microdisc Electrode	p. 103
EC' Mechanism at a Microdisc Electrode	p. 105
Size Effects on Half-Wave Potentials	p. 106
Extracting Parameters from Microdisc Chronoamperometry	p. 107
Extracting Parameters from Microdisc Chronoamperometry	p. 109
Voltammetry at Heterogeneous Surfaces	p. 111
Graphitic Electrodes	p. 111
Carbon Nanotubes and Their Reactivity	p. 113
Highly Ordered Pyrolytic Graphite and the Influence of Defects	p. 114
Advantages of Arrays	p. 115
Diffusional 'Cases'	p. 116
Geometry of a Regular Array	p. 117
Analysis of Diffusion to Electrode Arrays	p. 119
Partially Blocked Electrodes	p. 121
Cyclic Voltammetry: Coupled Homogeneous Kinetics and Adsorption	p. 123
EE Mechanism and Comproportionation	p. 123
EE mechanism: The Reduction of [(¿6-C6Me6)2Ru] [BF4]2	p. 124
EC2 Mechanism: The Reduction of the 2,6-Diphenyl Pyrylium Cation	p. 126
Analysis of an Unknown Reaction Mechanism	p. 128
EC Mechanism: Diethyl Maleate	p. 130
ECE Mechanism: p-chlorobenzonitrile	p. 133
ECE vs DISP 1: Voltammetry of Fluorescein	p. 135
Reduction of Anthracene in DMF	p. 137
CE Mechanism	p. 140
EC' Mechanism	p. 142
EC' Mechanism: Cysteine and Ferrocyanide	p. 143
EC' Mechanism: Oxygen and Anthraquinone	p. 145
Chronoamperometry of Adsorbed Species	p. 146
Voltammetry of an Ideal Adsorbed Species	p. 147
Non-Ideal Adsorbed Species	p. 150
Irreversible Electron Transfer and Adsorbed Redox Species	p. 153
Voltammetry of Ferrocyanide/Ferricyanide	p. 157
Hydrodynamic Electrodes	p. 159
Channel Electrodes and Limiting Currents	p. 159
Channel Electrodes and Reynolds Number	p. 160
Flow to Rotating Discs and in Channels	p. 161
Channel Electrodes and ECE Processes	p. 162
Channel Electrodes and ECE Processes	p. 164
Channel Electrodes and Entry Length	p. 167
Channel Electrodes and Diffusion Coefficients	p. 167
Channel Electrodes and Current Distribution	p. 169
Wall-Jet Electrodes and Current Distribution	p. 170
Wall-Jet Electrodes and Diffusion Coefficients	p. 170
Wall-Jet Electrode and a DISP 1 Process	p. 172
Wall-Jet Electrode and EC Processes	p. 173
Sono-Voltammetry	p. 177
Rotating Disc Electrodes and Reynolds Number	p. 178
Wall-Jet and Rotating Disc Electrodes	p. 178
Rotating Disc Electrodes and ECE Processes	p. 180
Voltammetry for Electroanalysis	p. 183
Electrochemical Sizing of Gold Surfaces	p. 183
Differential Pulse Voltammetry	p. 185
Square-Wave Voltammetry	p. 186
Square-Wave Voltammetry and Dissolved Oxygen	p. 187
Stripping Voltammetry	p. 188
Analysis of DNA	p. 189
The Clark Cell	p. 191
Calibration and Limits of Detection	p. 193
Enzyme Electrodes	p. 195
Glucose Biosensors	p. 196
Detection of Vitamin B12	p. 198
The Anodic Stripping Voltammetry of Industrial Effluent	p. 200
Adsorptive Stripping Voltammetry at Carbon Nanotube Modified Electrodes	p. 202
Surface Modified Electrodes	p. 205
Electron Transfer Rates at Carbon Electrodes	p. 208
Voltammetry in Weakly Supported Media: Migration and Other Effects	p. 211
Coulomb's Law	p. 211
The Nernst-Planck Equation	p. 212
Migration and the Electric Field	p. 215
Transport Numbers and Liquid Junction Potentials	p. 217
Transport Numbers and the Hittorf Method	p. 220
The Gouy-Chapman Equation	p. 221
Ohrnic Drop	p. 225
The Zero-Field Approximation	p. 227
Self-Supported Reduction of the Cobaltocenium Cation	p. 228
Voltammetry at the Nanoscale	p. 233
Debye Length vs Diffusion Layer Thickness	p. 233
Altered Electrode Kinetics and Reactivity at the Nanoscale	p. 235
Nanoparticles: Case 4 Behaviour	p. 236
'Coulomb Staircase' Effects	p. 238
Ultrafast 'Single Molecule' Voltammetry	p. 239
Thin-Layer Effects in Nanoscale Voltammetry	p. 242
Voltammetry in a Nanochannel	p. 244
Index	p. 249
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