Transient Techniques in Electrochemistry

ISBN-13: 9781461341475 / Angielski / Miękka / 2011 / 330 str.

Digby MacDonald

Opis

The study of electrochemical reactions by relaxation or transient techniques has expanded rapidly over the last two decades. The impetus for the develop ment of these techniques has been the desire to obtain quantitative data on the rates of "fast" electrochemical processes, including those coupled to homogeneous chemical reactions in solution. This has necessarily meant the development of techniques that are capable of delineating the effects of mass transport and charge transfer at very short times. The purpose of this book is to describe how the various transient techniques may be used to obtain the desired information. Emphasis is placed upon the detailed mathematical development of the subject, since this aspect is the most frequently ignored in other texts in this field. In any relaxation or transient technique for the study of rate processes, it is necessary to disturb the reaction from equilibrium or the steady state by applying a perturbing impulse to the system. The system is then allowed to relax to a new equilibrium or steady-state position, and. the transient (i. e., the response as a function of time) is analyzed to extract the desired kinetic information. In electrochemical studies the heterogeneous rate constants are, in general, dependent upon the potential difference across the interface, so that the perturbing impulse frequently takes the form of a known variation in potential as a function of time."

Spis treści

1. Introduction.- 1.1. Why Transient Techniques?.- 1.2. The Electrical Double Layer.- 1.3. The Kinetics of Charge Transfer Processes in the Steady State.- 1.3.1. Simple Charge Transfer Reactions.- 1.3.2. Complex Charge Transfer Reactions.- 1.4. General Current Equation.- 1.5. Surface Heterogeneity.- 1.6. Electrochemical Adsorption and Pseudocapacitance.- 2. Experimental Methods.- 2.1. Types of Perturbation.- 2.2. Cell and Electrode Design.- 2.2.1. Cell Design.- 2.2.2. Working-Electrode Design.- 2.2.3. Solution Preparation.- 2.3. The Electronics of Electrochemistry.- 2.3.1. Operational Amplifiers.- 2.3.2. The Voltage Follower.- 2.3.3. The Current Follower.- 2.3.4. The Voltage Adder.- 2.3.5. The Integrator.- 2.3.6. The Frequency Response of Operational Amplifiers.- 2.4. Potentiostats.- 2.4.1. Circuit Design.- 2.4.2. IR Compensation.- 2.5. Galvanostats.- 2.6. Transient Response.- 2.6.1. Introduction.- 2.6.2. Transform Analysis.- 3. The Mathematics of Diffusion.- 3.1. Introduction.- 3.2. Fick’s Laws of Diffusion.- 3.3. Laplace Transforms.- 3.4. Laplace Transformation of Fick’s Second Law.- 3.4.1. Planar Diffusion.- 3.4.2. Spherical Diffusion.- 3.4.3. Cylindrical Diffusion.- 3.4.4. Diffusion to an Expanding Plane.- 3.4.5. Initial and Boundary Conditions.- 3.5. Coupled Chemical/Electrochemical Processes.- 3.6. Inverse Laplace Transformation.- 3.7. Analysis in Laplace Space.- 3.8. Numerical Analysis.- 3.9. Digital Simulation.- 3.10. Analog Methods.- 4. Potential Step Chronoamperometry and Chronocoulometry.- 4.1. Introduction.- 4.2. Experimental.- 4.3. Simple Charge Transfer Reactions.- 4.3.1. Reversible Reactions.- 4.3.2. Irreversible Reactions.- 4.3.3. Quasi-Reversible Reactions.- 4.3.4. Metal Dissolution Reactions.- 4.3.5. Cyclic Potential Step Methods.- 4.4. Coupled Chemical/Electrochemical Processes.- 4.4.1. The CE Mechanism.- 4.4.2. The EC Mechanism.- 4.4.3. The ECE Mechanism.- 4.4.4. The Catalytic Mechanism.- 4.5. The Voltage Step Method.- 5. Chronopotentiometry.- 5.1. Introduction.- 5.2. Experimental.- 5.3. Simple Charge Transfer Reactions.- 5.3.1. Reversible Reactions.- 5.3.2. Irreversible Reactions.- 5.3.3. Quasi-Reversible Reactions.- 5.3.4. Parallel Charge Transfer Reactions.- 5.3.5. Consecutive Charge Transfer Reactions.- 5.3.6. Adsorption.- 5.4. Coupled Chemical/Electrochemical Processes.- 5.4.1. The CE Mechanism.- 5.4.2. The EC Mechanism.- 5.4.3. The ECE Mechanism.- 5.4.4. The Catalytic Mechanism.- 5.5. Current Reversal and Cyclic Methods.- 5.5.1. Current Reversal Techniques.- 5.5.2. Cyclic Techniques.- 5.6. Other Current Wave Forms.- 6. Linear Potential Sweep and Cylic Voltammetry.- 6.1. Introduction.- 6.2. Experimental.- 6.3. Double Layer Charging.- 6.4. Simple Charge Transfer Reactions.- 6.5. Coupled Chemical/Electrochemical Processes.- 6.5.1. The CE Mechanism.- 6.5.2. The EC Mechanism.- 6.5.3. The ECE Mechanism.- 6.5.4. The Catalytic Mechanism.- 6.5.5. Diagnostic Criteria.- 6.6. Adsorption.- 6.7. Convolution Potential Sweep Voltammetry.- 7. AC Impedance Techniques.- 7.1. Introduction.- 7.2. Experimental.- 7.2.1. AC Bridge Methods.- 7.2.2. Phase-Sensitive Detection.- 7.2.3. Direct Methods.- 7.3. Simple Charge Transfer Reactions.- 7.3.1. Reversible Reactions.- 7.3.2. Quasi-Reversible Reactions.- 7.3.3. Irreversible Reactions.- 7.3.4. Second and Higher Harmonics.- 7.3.5. Electrode Growth and Geometry Effects.- 7.4. Coupled Chemical/Electrochemical Processes.- 7.4.1. The CE Mechanism.- 7.4.2. The EC Mechanism.- 7.4.3. The ECE Mechanism.- 7.4.4. The Catalytic Mechanism.- 7.5. Complex Plane Analysis.- 7.6. Faradaic Rectification.- 7.6.1. Alternating Current Control.- 7.6.2. Alternating Potential Control.- 8. Surface Processes.- 8.1. Introduction.- 8.2. Potentiostatic Methods (Chronoamperometry).- 8.2.1. Mechanisms Involving Electrochemically Adsorbed Intermediates.- 8.2.2. Electrocrystallization.- 8.2.3. Film Growth.- 8.3. Galvanostatic Techniques.- 8.3.1. Deposition/Dissolution Processes.- 8.3.2. Passivation and Film Growth Phenomena.- 8.4. Linear Potential Sweep and Cyclic Voltammetry.- 8.4.1. Reactions Involving Adsorbed Reactants and/or Products.- 8.4.2. Passivation.- 8.5. AC Impedance Methods.- 8.5.1. The Method of Epelboin et al..- 8.5.2. The Method of Frumkin and Armstrong.- 8.5.3. Other Systems.- Appendix. Integration in Laplace Space.- References.