Effect of the Support on the Photocatalytic Water Oxidation Activity of Cobalt Oxide Nanoclusters

Abstract

Oxygen evolution from water driven by visible light is one of the key reactions for solar fuel production. In this paper, we investigated the effect of the support on photocatalytic water oxidation under visible light using cobalt oxide as a multielectron catalyst. A range of supported Co3O4 nanoclusters have been successfully synthesized via wet impregnation and bisolvent methods. Compared with the wet impregnation approach, the bisolvent method allowed us to obtain a high quality catalyst with all the Co3O4 nanoclusters formed inside the mesoporous support using hexane/water as the combination. The resulting catalyst consists of Co3O4 nanoclusters with a very small particle size (∼25 nm) and narrow size distribution. Catalytic water oxidation experiments were performed in [Ru(bpy)3]2+-persulfate (photochemical) and Ce4+/Ce3+ (chemical) systems, and it was found that smaller Co3O4 cluster sizes resulted in higher water oxidation activity. In addition, KIT-6 was found to be a better support than SBA-15, w...