The Potential of the Manganese Dioxide Electrode and the Surface Composition of the Oxide

Abstract

When manganese dioxide is heated, the electrode potential decreases with the heating temperature. This potential decrease cannot be explained as a phase transformation nor as an ordinary decomposition of to . A lower oxide film is formed on the surface of when it is heated at temperatures up to 450°C. The potential decrease on heating can be explained as the result of the lower oxide film formation, the potential of manganese dioxide depending on the surface oxidation state. The reaction of Mn⁺⁺ in slightly alkaline electrolyte with gives a similar decrease in potential explainable as a surface effect.