Modern Aspects of Electrochemistry No. 13

The present volume contains five chapters covering areas of contemporary interest in the fields of electrolyte solutions, the state of solvent molecules at electrode surfaces, charged colloid interfaces, surface chemistry of oxide electrodes and electro­ chemistry, and bioelectrochemistry of charge transfer complexes. The first chapter, by Barthel, Wachter, and Gores, covers the topic of conductance of nonaqueous pro tic and aprotic electro­ lyte solutions. This field is not only of intrinsic interest in itself, illustrating the important departures of ion-transport behavior in organic solvents from that, more well known, in water, but the information and extensive new data presented in this chapter will be of interest to those working with nonaqueous alkali-metal batteries where the conductivity and ion-association behavior of electrolytes in various solvents other than water is of great importance. The second chapter is devoted to a very fundamental and ubiquitous aspect of electrochemistry of electrodes: the state of solvent molecules, adsorbed and oriented, at their surfaces. The role of solvent adsorption and orientation in double-layer proper­ ties, it will be recalled, remained poorly understood until the early 1960s. This chapter, by Trasatti, gives a thorough account of the present state of knowledge of solvent orientation at electrode interfaces and of the unsuspected (until recent years) role it plays in properties of the double layer and in determining the potential profile at charged metal surfaces in solution.

1 Temperature Dependence of Conductance of Electrolytes in Nonaqueous Solutions.- I. Introduction.- II. Experimental Aspects.- 1. Temperature Control.- 2. Conductance Measurements.- 3. Organic Solvents.- III. Dilute Electrolyte Solutions.- 1. Conductance Equations.- 2. Thermodynamics of Ion-Pair Formation.- 3. Ionic Conductance.- 4. Analysis of Experimental Data.- 5. Results and Discussion.- IV. Concentrated Electrolyte Solutions.- 1. Survey.- 2. Analysis of Experimental Data.- 3. Electrolytes in Pure Organic Solvents.- 4. Organic Solvent Mixtures.- References.- 2 Solvent Adsorption and Double-Layer Potential Drop at Electrodes.- I. Introduction.- 1. Scope of the Chapter.- 2. Historical Survey.- II. Water Dipole Contribution to the Potential of Zero Charge.- 1. Basic Double-Layer Model.- 2. Relative Values of Surface Potential of Water at Various Metals.- 3. Surface Potential of Water at Mercury.- 4. Surface Potential of Water at the Free Surface.- 5. Surface Potential of Water at Other Metals.- III. Relation of Surface Potential to Strength of Water Adsorption.- 1. Hydrophilicity of Metals.- 2. The Interaction Parameter of Metal Surfaces.- 3. Additional Evidence for the Hydrophilicity Scale.- 4. Dielectric Aspects.- IV. Description of the Structure of Interfacial Water.- 1. Theoretical Structural Models.- 2. Comparison with Experiments.- 3. The Idea of Water Clusters.- V. Electric Field Effects.- 1. Charge Dependence of Water Dipole Orientation.- 2. The Capacity Hump.- 3. The Charge for Zero Net Dipole Orientation.- VI. Temperature Effects.- 1. Temperature Dependence of Water Dipole Orientation.- 2. Surface Excess Entropy in the Inner Layer.- VII. Suggestions for a Possible Alternative Model.- VIII. Nonaqueous Solvents.- 1. Qualitative Aspects.- 2. Quantitative Aspects.- References.- 3 Electrochemical Aspects of Adsorption on Mineral Solids.- I. Introduction.- II. Basic Principles.- III. Charge Generation.- IV. Electrostatic Adsorption.- V. Lateral Interaction between Adsorbates.- VI. Chemical Forces.- VII. Chemical State of the Adsorbate.- VIII. Miscellaneous.- IX. Application of Boundary Tension and Contact Angle Measurements.- X. Adsorption Kinetics.- XI. Current Research Trends.- References.- 4 Application of Auger and Photoelectron Spectroscopy to Electrochemical Problems.- I. Introduction.- 1. Methods.- 2. Surface Analysis.- II. Auger Electron Spectroscopy.- 1. Physical Process.- 2. The Auger Spectrum.- 3. Instrumentation.- 4. Qualitative Analysis.- 5. Quantitative Analysis.- 6. Chemical Effects.- 7. Background Subtraction and Deconvolution.- 8. Electron Beam Effects.- III. X-Ray-Excited Photoelectron Spectroscopy.- 1. Physical Process.- 2. The Photoelectron Spectrum.- 3. Instrumentation.- 4. Elemental Analysis.- 5. Quantitative Analysis.- 6. Chemical Effects.- 7. Determination of Valence Band Density of States.- 8. Deconvolution Methods.- 9. X-Ray-Excited AES.- 10. X-Ray-Induced Damage.- IV. AES and XPS for Surface Analysis.- 1. Escape Depth.- 2. Distinction between Surface and Bulk Contributions.- 3. Profile.- 4. Surface Roughness.- 5. Structure.- V. Surface Analysis Applied to Electrocatalysts.- 1. Oxide Layers on Noble Metals.- 2. RuO2-Based Film Electrodes.- 3. Characterization of Electrode Surfaces in Connection with Adsorption Studies.- VI. Application of AES and XPS to Passivity and Corrosion Studies.- 1. AES Studies.- 2. XPS Studies.- VII. Concluding Remarks.- References.- 5 An Introduction to the Electrochemistry of Charge Transfer Complexes II.- I. Introduction.- II. Ionics.- 1. Donicity.- 2. Conductivities.- 3. Charge Carriers.- 4. Solvent Interactions.- 5. Colloid and Surface Complexations.- 6. Stochastic Processes.- III. Electrodics.- 1. Complex Formation as an Electrode Reaction.- 2. Electrocatalysis and Heterogeneous Catalysis.- 3. Electrochemical Methods.- IV. Ternary and Proton Transfer Complexes.- 1. Ternary Complexes.- 2. Proton Complexes.- V. Charge Transfer Complexes as Electrochemical Energy Storage Devices.- References.