Au25 cluster-loaded SrTiO3 water-splitting photocatalyst; preparation and elucidation of the effect of cocatalyst refinement on photocatalytic activity

Water-splitting photocatalysts have attracted much attention for decades as materials to produce clean and renewable hydrogen (H2) as a fuel. In this study, we succeeded in precisely loading ultrafine gold cocatalyst particles (Au25 clusters) on the water-splitting photocatalyst SrTiO3 using glutathionate-protected Au25 clusters as a precursor. Photocatalysis experiments using the obtained photocatalyst revealed that the ultraminiaturization of the Au cocatalyst on SrTiO3 improves its water-splitting activity. The main reason for this improvement was attributed to the acceleration of the H2-evolution reaction caused by the ultra-miniaturization of the cocatalyst. This effect of refining the cocatalyst differs from that of Au-loaded BaLa4Ti4O15. These results demonstrate that the effect of ultra-miniaturization of the cocatalyst on photocatalytic activity varies depending on the photocatalyst