Kinetics of the Chemical and Electrochemical Reduction of Platinum Black Surface Oxides

Abstract

A comparative study of the reductions of platinum black surface oxides by electrochemical (at constant current) and chemical means (by propane) has been made. From the nature of the rates of the chemical reduction, from potential‐time behavior, and from the two breaks observed in potential vs. logarithm coulombs for reductions at <1.60v oxidation, two types of surface oxides at the platinum black electrode have been observed. The chemical reduction of the platinum black surface oxide, when the electrode is oxidized to a potential in the range of 1.30–1.60 v vs. hydrogen electrode, is zero order with respect to oxide formation and has a rate of or “67 ma/cm2.” The zero order reaction observed suggests that the oxygen is strongly adsorbed. The chemical reduction rate of the surface oxide formed at potentials less than 1.30v, is not constant, and the oxygen is held loosely at the platinum surface.