The Cathodic Reduction of Oxygen on Platinum in Alkaline Solutions

Measurements with rotating disk and r ing/disk electrodes have been used to elucidate the reaction paths for oxygen reduction on platinum in concen-trated alkaline electrolyte. It is concluded that oxygen is reduced to hydrogen peroxide at potentials between the open circuit voltage and 0.4V vs. a reversi-ble hydrogen electrode. Between 0.4 and 0.0V vs. a reversible hydrogen lec-trode, oxygen is reduced to OH- with peroxide as an intermediate product. The effect of hydrogen peroxide decomposition on the limiting current density for oxygen reduction at a rotating disk electrode and on the value of the ring current of a rotating r ing/disk electrode is discussed. Studies on the electrochemical reduction of oxygen have been stimulated in the last few years by the interest in fuel cells and metal /a i r batteries. It has been previously demonstrated that hydrogen peroxide is the product of oxygen reduction on carbon elec