Electrochemical oxidation of hydrogen peroxide at platinum electrodes. Part II: effect of potential

The electrochemical oxidation of H 2O 2 at a platinum rotating disc electrode was studied at pH 7.26 for the [H 2O 2] range 0–70 mM, rotation rates 630–10000 rpm and anodic potential +264 to +712 mV vs Ag/AgCl using staircase potentiometry. A mechanism is proposed to account for the steady-state current as a function of rotation rate, [H 2O 2] and anodic potential. This mechanism involves reversible binding of H 2O 2 to electrochemically generated Pt(II) surface sites, reduction of the site and inhibiting competitive adsorption of H + and O 2. Potential-invariant values of the constants for H 2O 2, H + and O 2 binding are determined and the rate constants for the reduction and the re-oxidation of the binding site as a function of potential are evaluated.