Mass and charge transfer kinetics and coulometric current efficiencies. Part VI. The pre-treatment of solid electrodes, and a review of the effects of oxidation of platinum

Abstract

The nature and condition of working electrode surfaces are set in the context of reaction speeds and current efficiencies. The formation of films and their effects are examined for platinum and other metals and alloys. Adsorption and specific adsorption on electrode surfaces are briefly reviewed. An attempt is then made critically to appraise the current state of the art in respect of the activation and deactivation of electrodes. Methods of cleaning electrodes are canvassed. The more significant theories of activation and deactivation are reviewed with specific reference to platinum electrodes. These theories include the impurity theory, the platinisation theory and the various oxygen-containing surface theories. For the last, the formation of oxides, the measurement of film thickness, the film thickness and the nature of the oxide reducible at 0·6 V are discussed, followed by a selective review of the oxygen-bridge theory, the half-reduced oxide theory and the platinum-oxygen alloy theory. Tentative conclusions are reached. Finally, gold electrodes and their behaviour are briefly examined.