Synthesis of α-Ga(2)O(3) by Water Oxidation of Metallic Gallium as a Photocatalyst for CO(2) Reduction with Water

[Image: see text] We have succeeded to synthesize gallium oxide consisting of α-phase (α-Ga(2)O(3)) with the calcination of GaOOH obtained by a direct reaction of liquid Ga metal with water for the first time and found that α-Ga(2)O(3) exhibits photocatalytic activity for CO(2) reduction with water and water splitting as well. The calcination above 623 K converted GaOOH to α-Ga(2)O(3), and the samples calcined at 723–823 K were well crystallized to α-Ga(2)O(3) and promoted photocatalytic CO(2) reduction with water, producing CO, H(2), and O(2). This is observed for the first time that α-Ga(2)O(3) without a cocatalyst has shown very high photocatalytic activity for the conversion of CO(2) to CO.