Electroanalytical Chemistry

A Series of Advances: Volume 17

Allen J. Bard, Allen J. Bard

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000447613
• Edition: 1
• Topic: Scienze fisiche
• Subtopic: Chimica

This book examines the metal/solution interface with the electrochemical quartz crystal microbalance, exploring electrostatic adsorption, metal deposition, and roughness. It explores the indirect laser-induced temperature-jump method for characterizing fast interfacial electron transfer.

CARBON ELECTRODES: STRUCTURAL EFFECTS ON ELECTRON TRANSFER KINETICS

Richard L. McCreery

The Ohio State University
Columbus, Ohio

1. I. Introduction and Scope
2. II. Bulk Carbon Structure and Preparation
   1. A. Structural variables in sp² carbon
   2. B. Bulk characterization of sp² carbon
   3. C. Preparation and properties of bulk carbon materials
3. III. Structure of Carbon Electrode Surfaces
   1. A. Principal surface variables
   2. B. Structural characterization of carbon surfaces
   3. C. Electrochemical characterization of carbon electrodes
4. IV. Carbon Electrode Preparation and Performance
   1. A. Highly ordered pyrolytic graphite
   2. B. Pyrolytic graphite
   3. C. Carbon paste, graphite rods, carbon composites
   4. D. Glassy carbon
   5. E. Carbon fiber electrodes
   6. F. Carbon film electrodes
5. V. Conclusions
   1. A. Electron transfer reactivity
   2. B. Capacitance of carbon electrodes
   3. C. Adsorption
6. References

I. INTRODUCTION AND SCOPE

Since the use of charcoal electrodes by Michael Faraday, carbon has been a widely used and extensively studied electrode material for electrochemical applications. To provide a broad economic perspective, about $35 billion of the 1985 U.S. gross national product resulted directly from electrochemistry [1], a significant fraction of which involved carbon electrodes. A recent monograph [2] covers both fundamental and applied aspects of carbon electrochemistry, with an emphasis on carbon black. A symposium proceedings volume appeared in 1984 [3], and review articles of interest to analytical chemists are in print [4-8]. These references establish the diversity of applications of carbon materials in electrochemistry and provide a perspective for the current chapter.

The suitability of an electrode material for analytical applications is dictated by electron transfer rate, background current, mechanical properties, stability, etc. Analytically useful electrodes may differ substantially from those used in electrosynthesis or fuel cells, since the objectives are quite different. In many practical cases, the choice of a carbon material for analytical applications is determined by convenience or empirical observations, without regard to carbon structure. Due mainly to difficulties in preparing and characterizing well-defined carbon surfaces, there has been limited progress in relating surface structure to electroanalytical performance.

This chapter is divided into four major sections, with the overall goal of describing a relationship between carbon electrode structure and electroanalytical performance. Particular emphasis will be placed on structural variables that affect electron transfer kinetics and voltammetric background current, since these variables usually determine the analytical utility of an electrode. In the first major section, the structure and bulk properties of various sp² carbon materials will be described. In the second section, the carbon surface will be considered, with particular attention to surface structure and characterization. Third, the electrochemical consequences of bulk structure and surface preparation will be discussed, with particular emphasis on the relationship between surface structure and heterogeneous electron transfer rate. Finally, a model of the carbon electrode surface will be proposed which accounts for the experimental observations. Rather than attempt to comprehensively discuss carbon structure and properties, the discussion will be limited to those aspects of carbon which are known to affect electrode kinetics and background current. In order to keep the scope of the chapter at a manageable level, the discussion will be limited to experiments in aqueous media. With the exception of surface oxidation, chemical modifications of carbon electrodes will not be addressed. These constraints on scope force selectivity in the choice of literature citations and the exclusion of a large body of valuable published results. The omission of many excellent papers involving carbon electrodes permits a tighter focus on the effects of carbon structure on electron transfer kinetics.

II. BULK CARB...