Reaction behavior on titanium oxide cathode surface in electrolytic reduction process of selenate

Direct electrochemical reduction of selenate in aqueous solution was performed using a titanium oxide-coated cathode to investigate selenium reduction behaviors on the oxide film surface. The oxide films were synthesized by anodization with different numbers of stages and electrolyte compositions. Selenium reduction proceeded at a more noble potential on the oxide films compared with the raw titanium plate. However, the Faraday efficiency of selenate reduction decreased when the oxide film-coated cathodes were used. On these films, the reduction of titanium compounds other than TiO 2 , and the formation of TiOOH, resulting from Ti (IV) reduction and proton insertion, occurred concurrently with selenate reduction. This led to a decrease in Faraday efficiency, and the behavior of these reactions varied depending on the synthesis conditions of the oxide films.