Photocatalytic Activity of Metal Oxide Supported Gallium Oxide for CO2 Reduction with Water

We have examined photocatalytic activities of Ga2O3 supported by various metal oxides for water splitting and CO2 reduction with water under UV light irradiation. The Ga2O3 photocatalyst supported by metal oxides was prepared by an impregnation method. We have found that some oxides used as a supporting oxide of Ga2O3 photocatalyst improve activities of water splitting and CO2 reduction. In particular, the CO production rates are well correlated to various properties of the supporting oxide. These oxides satisfy the following three criteria significantly enhancing the CO production rate. (1) Their band gap is wider than that of Ga2O3 and the position of its conduction band is at a negative potential with respect to that of Ga2O3. (2) They are not miscible with Ga2O3 and (3) mixed phases of alpha and gamma or defective gamma phase of Ga2O3 are well dispersed on them exhibiting columnar shape. These criteria would be useful for further improvement of the activity for photocatalytic CO2 reduction with water by Ga2O3.