Analytical Electrochemistry

Preface ix

Abbreviations and Symbols xi

1 Fundamental Concepts 1

1.1 Why Electroanalysis? 1

1.2 Faradaic Processes 2

1.2.1 Mass-Transport-Controlled Reactions 4

1.2.1.1 Potential-Step Experiment 6

1.2.1.2 Potential Sweep Experiments 7

1.2.2 Reactions Controlled by the Rate of Electron Transfer 9

1.2.2.1 Activated Complex Theory 12

1.3 Electrical Double Layer 14

1.4 Electrocapillary Effect 18

1.5 Supplementary Reading 19

References 20

Questions 21

2 Study of Electrode Reactions and Interfacial Properties 22

2.1 Cyclic Voltammetry 22

2.1.1 Data Interpretation 24

2.1.1.1 Reversible Systems 24

2.1.1.2 Irreversible and Quasi-reversible Systems 25

2.1.2 Study of Reaction Mechanisms 26

2.1.3 Study of Adsorption Processes 29

2.1.4 Quantitative Applications – Fast-Scan Cyclic Voltammetry 30

2.2 Spectroelectrochemistry 32

2.2.1 Experimental Arrangement 32

2.2.2 Principles and Applications 33

2.2.3 Electrochemiluminescence 35

2.2.4 Optical Probing of Electrode/Solution Interfaces 36

2.3 Scanning Probe Microscopy 37

2.3.1 Scanning Tunneling Microscopy 37

2.3.2 Atomic Force Microscopy 38

2.3.3 Scanning Electrochemical Microscopy 40

2.4 Electrochemical Quartz Crystal Microbalance 43

2.5 Impedance Spectroscopy 45

References 47

Examples 50

Questions 52

3 Controlled-Potential Techniques 54

3.1 Chronoamperometry 54

3.2 Polarography 56

3.3 Pulse Voltammetry 59

3.3.1 Normal-Pulse Voltammetry 59

3.3.2 Differential-Pulse Voltammetry 60

3.3.3 Square-Wave Voltammetry 62

3.3.4 Staircase Voltammetry 65

3.4 AC Voltammetry 66

3.5 Stripping Analysis 67

3.5.1 Anodic Stripping Voltammetry 68

3.5.2 Potentiometric Stripping Analysis 71

3.5.3 Adsorptive Stripping Voltammetry and Potentiometry 72

3.5.4 Cathodic Stripping Voltammetry 74

3.5.5 Abrasive Stripping Voltammetry 75

3.5.6 Applications 75

3.6 Flow Analysis 75

3.6.1 Principles 77

3.6.2 Cell Design 79

3.6.3 Mass Transport and Current Response 81

3.6.4 Detection Modes 83

References 85

Examples 88

Questions 90

4 Practical Considerations 93

4.1 Electrochemical Cells 93

4.2 Solvents and Supporting Electrolytes 95

4.3 Oxygen Removal 95

4.4 Instrumentation 96

4.5 Working Electrodes 101

4.5.1 Mercury Electrodes 102

4.5.2 Solid Electrodes 103

4.5.2.1 Rotating Disk and Ring-Disk Electrodes 104

4.5.2.2 Carbon Electrodes 106

4.5.2.3 Metal Electrodes 109

4.5.3 Printed Electrodes and Devices 110

4.5.3.1 Planar Screen-Printed Electrodes 110

4.5.3.2 3D-Printed Electrochemical Cells and Electrodes 112

4.5.4 Chemically Modified Electrodes 113

4.5.4.1 Self-Assembled Monolayers 114

4.5.4.2 Carbon-Nanotube-Modified Electrodes 115

4.5.4.3 Graphene-Based Electrodes 116

4.5.4.4 Sol–Gel Encapsulation of Reactive Species 117

4.5.4.5 Electrocatalytic Modified Electrodes 117

4.5.4.6 Preconcentrating Electrodes 118

4.5.4.7 Permselective Coatings 119

4.5.4.8 Conducting Polymers 122

4.5.5 Microscale and Nanoscale Electrodes 124

4.5.5.1 Diffusion at Microelectrodes 126

4.5.5.2 Configurations of Microelectrodes 126

4.5.5.3 Composite Electrodes 128

4.5.6 Microneedle Electrodes and Arrays 130

References 132

Examples 137

Questions 137

5 Potentiometry 139

5.1 Principles of Potentiometric Measurements 139

5.2 Ion-Selective Electrodes 145

5.2.1 Glass Electrodes 145

5.2.1.1 pH Electrodes 145

5.2.1.2 Glass Electrodes for Other Cations 148

5.2.2 Liquid Membrane Electrodes 148

5.2.2.1 Ion-Exchanger Electrodes 150

5.2.2.2 Neutral Carrier Electrodes 151

5.2.3 Solid-State Electrodes 154

5.2.4 Solid-Contact ISE: Eliminating the Internal Filling Solution 157

5.3 On-line, On-site, In Situ, and In Vivo Potentiometric Measurements 160

References 164

Examples 167

Questions 168

6 Electrochemical Sensors 170

6.1 Electrochemical Biosensors 171

6.1.1 Enzyme?Based Electrodes 171

6.1.1.1 Practical and Theoretical Considerations 171

6.1.1.2 Enzyme Electrodes of Analytical Significance 175

6.1.2 Affinity Biosensors 182

6.1.2.1 Immunosensors 182

6.1.2.2 Aptamer?Based Electrochemical Biosensors 185

6.1.2.3 DNA Hybridization Biosensors 186

6.1.2.4 Electrochemical Sensors Based on Molecularly Imprinted Polymers 189

6.2 Gas Sensors 189

6.2.1 Carbon Dioxide Sensors 190

6.2.2 Oxygen Electrodes 191

6.3 Solid-State Devices 192

6.3.1 Ion?Selective Field Effect Transistors 192

6.3.2 Microfabrication of Solid?State Sensor Assemblies 194

6.3.3 Photolithographic Sensor Fabrication Techniques 194

6.3.4 Micromachined Analytical Microsystems 195

6.3.5 Paper?Based Electroanalytical Devices 196

6.4 Sensor Arrays 197

6.5 Wearable Electrochemical Sensors 200

References 203

Examples 210

Questions 211

Index 213