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

The electrochemical oxidation of H₂O₂ at a platinum rotating disc electrode was studied at pH 7.26 for the [H₂O₂] 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, [H₂O₂] and anodic potential. This mechanism involves reversible binding of H₂O₂ to electrochemically generated Pt(II) surface sites, reduction of the site and inhibiting competitive adsorption of H⁺ and O₂. Potential-invariant values of the constants for H₂O₂, H⁺ and O₂ 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.