Reactions of oxygen and hydrogen peroxide at silver electrodes in alkaline solutions

Abstract

The intermediate peroxide scheme for the oxygen electrode has been tested by experiments on oxygen reduction and hydrogen peroxide decomposition at silver electrodes in potassium hydroxide solutions (0·1, 1·0 and 5·0 M) at 25°C. The scheme is found appropriate in interpreting the observations, and data are obtained for the specific rate of three of the four one-electron steps involved in the reduction of oxygen to water. The decomposition of hydrogen peroxide occurs at a diffusion-limited rate and gives a mixed potential, V(nhe) = 0·94–0·059 pH, when the peroxide concentration exceeds a low limit (10−6 M in 1 M KOH). The silver-dissolution reaction exhibits essentially pure diffusion polarization and with the oxygen-reduction reaction determines the open-circuit potential of silver when the peroxide content of the solution is low. The results are compared with previous data on silver and on other electrode materials.