Effect of oxide thickness on the rates of some redox reactions on a platinum electrode

Abstract

The type of oxide formed anodically on Pt, as well as its thickness, varies depending on the potential against time conditions of formation. The effects of oxide type and thickness on the kinetics of two redox reactions (Mn^III/Mn^II and Ce^IV/Ce^III) in aqueous medium have been investigated. ‘Oxide I’ is an electronically conducting species whose thickness did not affect the kinetics of the above reactions, in conflict with others' results. It is suggested that in these cases inadequate control of oxide-formation conditions resulted in the presence of ‘oxide II’, whose electronic and electrocatalytic properties are entirely different from those of oxide I.