The redox reaction of hydrogen peroxide at an Au(100) electrode: Implications for oxygen reduction kinetics

Abstract The redox reaction of hydrogen peroxide (O 2  + 2H +  + 2e ⇄ H 2 O 2 ) at an Au(100) electrode/0.1 M HClO 4 interface and the kinetic H–D isotope effect for O 2 reduction have been investigated. It was found that i) the kinetics for electrochemical oxidation of H 2 O 2 to O 2 are very fast, occurring at a potential very close to its equilibrium potential ( E O 2 / H 2 O 2 eq ); ii) the kinetics for O 2 reduction to H 2 O 2 are much slower than those for H 2 O 2 oxidation, with a H–D kinetic isotope effect of above two; and iii) the onset overpotential of H 2 O 2  + 2H +  + 2e → 2H 2 O is ca. 1.4 V. Mechanistic insight and the origin for the high overpotential at the onset for O 2 reduction at Au(100) are discussed.