A study on characteristics of an electrolytic–photocatalytic reactor using an anode coated with TiO2

A photocatalytic-electrolysis reactor using an anode coated with a TiO2 thin film of an anatase structure, a low surface resistivity, and a large surface area has shown an enhancement of TiO2 photocatalytic reaction efficiency by a reduction of the recombination of photogenerated electron–hole pairs. At the photocatalytic anode under UV irradiation and with a potential to generate oxygen evolution being applied, the photocatalytic enhancement was about 90% because of suppression of the recombination of holes and electrons by taking out forcedly the generated electrons through an external bias into a cathode and by the oxygen generated by the electrolytic reaction acting as an acceptor to the electrons. The photocatalytic enhancement effect occurred only when the cell voltage applied to the photocatalytic-electrolysis reactor was over a certain value. The photocatalytic reaction observed on the catalytic oxide electrodes of RuO2 and IrO2 was because of the existence of TiO2 on the electrode surface, which resulted from the oxidation of Ti substrate itself during sintering for the fabrication of the electrodes.