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 Au 25 (SR) 18 nanoclusters (R:CH 2 CH 2 Ph) and TiO 2 nanocrystals. The effects of Au 25 (SR) 18 nanoclusters on the photocatalytic activity of TiO 2 nanocrystals were evaluated in the reaction of photocatalytic degradation of methyl orange. The loading of Au 25 (SR) 18 nanoclusters onto TiO 2 results in strong visible light absorption by the composite and, more importantly, a 1.6 times increase in visible light photocatalytic activity. Furthermore, the Au 25 (SR) 18 /TiO 2 composite nanostructure exhibits high stability in recycling tests. The Au 25 (SR) 18 nanolusters dispersed on the TiO 2 surface can act as a small-band-gap semiconductor to absorb visible light, giving rise to electron–hole separation and producing singlet oxygen ( 1 O 2 ). Both the generated hydroxyl radicals (HO • ) and 1 O 2 are rationalized to be responsible for the decomposition of the dye.