THE IMPORTANCE OF ANODIC DISCHARGE OF H2O IN ANODIC OXYGEN-TRANSFER REACTIONS

Difference voltammetry at rotated disk electrodes was applied to a study of several anodic. O-transfer reactions that appear to occur concurrently with O2 evolution. This voltammetric technique was useful for extracting the rotation-dependent component of the total current from the large, virtually rotation-independent current for O2 evolution. Data for oxidation of I- at Pt, Au, Pd, Ir, and glassy carbon electrodes show that the E1/2 for IO3- production is correlated with the overpotential for O2 evolution at these electrode materials. Data obtained at an Ir electrode for various reactions with widely varying E(o) values reveal uniform E1/2 values closely correlated with the potential for onset of O2 evolution in both alkaline and acidic solutions. The results support the conclusion that the anodic discharge of H2O is a prerequisite of these anodic O-transfer mechanisms.