Stable Au25(SR)18/TiO2 Composite Nanostructure with Enhanced Visible Light Photocatalytic Activity

We report the visible light photocatalytic properties of a composite material consisting of Au25(SR)18 nanoclusters (R:CH2CH2Ph) and TiO2 nanocrystals. The effects of Au25(SR)18 nanoclusters on the photocatalytic activity of TiO2 nanocrystals were evaluated in the reaction of photocatalytic degradation of methyl orange. The loading of Au25(SR)18 nanoclusters onto TiO2 results in strong visible light absorption by the composite and, more importantly, a 1.6 times increase in visible light photocatalytic activity. Furthermore, the Au25(SR)18/TiO2 composite nanostructure exhibits high stability in recycling tests. The Au25(SR)18 nanolusters dispersed on the TiO2 surface can act as a small-band-gap semiconductor to absorb visible light, giving rise to electron–hole separation and producing singlet oxygen (1O2). Both the generated hydroxyl radicals (HO•) and 1O2 are rationalized to be responsible for the decomposition of the dye.