Photosensitized Electrolytic Oxidation of Sulfate on an Illuminated Titanium Dioxide Semiconductor Electrode

Abstract

Sulfate and hydrogensulfate ions were oxidized to peroxodisulfate ions on an illuminated titanium dioxide single crystal electrode. The oxidation potential was founded to be about 2.7 volt more negative than their standard oxidation potentials. These reactions seems to proceed through a direct transfer of photoexcited holes in the valence band to these sulfate ion species. The rate of the oxidation was affected by the composition of the electrolyte. The current efficiency for the formation of peroxodisulfate increased with increasing concentration of sulfuric acid. This behavior can be explained in terms of energy diagram for semiconductorelectrolyte interface.