XPS study of the MnO2 electrode in borate solution during the discharge process

The thin hydrous manganese oxide electrodeposited on gold has been studied using X-ray Photoelectron Spectroscopy (XPS). The oxygen 1s spectrum changes during the cathodic discharge process and can be deconvoluted into three components: MnO, MnOH or MnOH2 and water adsorbed. The surface composition of the film, MnOx(OH)y(OH2)z, has been described according to the O 1s spectrum analysis. The x and y + z values were calculated from the Io/Im ratio peak intensities. The oxidation number of Mn has been calculated at different potentials during the manganese oxide reduction. These values indicate that MnO2 is reduced to Mn(III) in borate solutions at pH 9.2