Synthesis of α-Ga2O3 by Water Oxidation of Metallic Gallium as a Photocatalyst for CO2 Reduction with Water.

We have succeeded to synthesize gallium oxide consisting of α-phase (α-Ga2O3) with the calcination of GaOOH obtained by a direct reaction of liquid Ga metal with water for the first time and found that α-Ga2O3 exhibits photocatalytic activity for CO2 reduction with water and water splitting as well. The calcination above 623 K converted GaOOH to α-Ga2O3, and the samples calcined at 723-823 K were well crystallized to α-Ga2O3 and promoted photocatalytic CO2 reduction with water, producing CO, H2, and O2. This is observed for the first time that α-Ga2O3 without a cocatalyst has shown very high photocatalytic activity for the conversion of CO2 to CO.