Enhanced Electrochemical Oxidation of H2O2 at Iodine-Modified Gold Electrode in Alkaline Media

Abstract

In this report, electrochemical oxidation of hydrogen peroxide at the bare polycrystalline gold [Au (poly)] electrode and the Au (poly) electrode modified with a submonolayer of iodine (sub I) [sub (poly)] electrode in solution has been described. At the bare Au (poly) electrode, electrochemical oxidation of proceeds probably via a rate-determining chemical step, i.e., adsorption of at the Au (poly) electrode. While modification of the Au (poly) electrode by the sub I results in a change of the reaction pathway to a diffusion-controlled one and a tremendous enhancement of the oxidation current. Five times larger oxidation peak current has been achieved at the sub (poly) electrode compared with the potential-independent oxidation plateau current at the bare Au (poly) electrode. Strong electrostatic attraction between the anionic molecules and the iodine-adlayer-induced positively polarized Au (poly) electrode surface has been proposed to be responsible for the enhancement of the electrode activity toward oxidation. The effect of surface coverage of I and the concentration of on the oxidation of at the sub (poly) electrode has also been investigated. Experimental investigation has been performed on the basis of the open-circuit potential measurement and cyclic and linear sweep voltammetric studies.