Reduction of oxygen to water on cobalt-nitride thin film electrodes prepared by the reactive rf sputtering technique

Abstract

Electrochemical reduction of oxygen was carried out on amorphous cobalt-nitride (Co x N) thin film electrodes prepared by the reactive RF sputtering technique. The onset potential of the oxygen reduction current in the Co x N electrode in neutral electrolyte solutions was close to that on a platinum metal electrode, which is known to be the most efficient material for oxygen reduction. Measurements with rotating-disk electrodes (RDEs) and rotating ring-disk electrodes (RRDEs) showed that reduction of oxygen to water (the four-electron-transfer type) proceeded on the Co x N electrodes, unlike that on Co metal electrodes, where only the two-electron-transfer type reduction to hydrogen peroxide took place. The reason for the improved electrocatalytic activity by nitridation is discussed briefly.