Photocatalytic Activity of Ga(2)O(3) Supported on Al(2)O(3) for Water Splitting and CO(2) Reduction

[Image: see text] We have examined the photocatalytic activity of Ga(2)O(3) supported on Al(2)O(3) (Ga(2)O(3)/Al(2)O(3) catalyst) without a noble metal cocatalyst for water splitting and reduction of CO(2) with water under UV light irradiation by changing the loading amount of Ga(2)O(3). All prepared Ga(2)O(3)/Al(2)O(3) catalysts show photocatalytic activities for both water splitting and CO(2) reduction, and their activities are significantly improved compared to those of nonsupported Ga(2)O(3) and Al(2)O(3). The water splitting is dominated for Ga(2)O(3)/Al(2)O(3) with less than 1.0 vol % of Ga(2)O(3) loaded, whereas the CO(2) reduction, for higher Ga(2)O(3)-loaded samples (2.6, 4.2 vol %). Crystalline structure characterizations of Ga(2)O(3)/Al(2)O(3) catalysts indicate that active sites for both reactions are different. The water splitting proceeds on nanometer-sized Ga(2)O(3) rods dispersed on an Al(2)O(3) support consisting of a little distorted α-Ga(2)O(3) phase. On the other hand, the CO(2) reduction proceeds on sub-micrometer-sized Ga(2)O(3) particles consisting of mixed phases of α-Ga(2)O(3) and γ-Ga(2)O(3) or with appearance of boundaries between the α and γ phases, which plays a critical role. Al(2)O(3) used as the support of the Ga(2)O(3) particles does not seem to play an important role in the photocatalytic CO(2) reduction.