Size transformation of Au nanoclusters for enhanced photocatalytic hydrogen generation: Interaction behavior at nanocluster/semiconductor interface

Recently, atomically precise metal nanoclusters (NCs) become a new class of photosensitizer for light energy conversion in metal-cluster-sensitized semiconductor (MCSS) system. However, fundamental understanding for the suitable combination of NCs and semiconductor is still unclear. Aside from aspects of light harvesting, energy level alignment and catalytic activity, interfacial interaction behavior at NCs/semiconductor interface is also crucial due to its important influence in charge transportation. In this work, the interface interaction between Au NCs and TiO 2 is examined by precise transformation of Au NCs from Au 22 (SG) 18 to Au 18 (SG) 14 , as well as its effect on photocatalytic hydrogen production activity. From the optical, charge transport and solid-states spectroscopy analyses, it is able to display that precisely tuning the number of core atoms from Au 22 (SG) 18 to Au 18 (SG) 14 results in the strong interface interaction between Au NCs and TiO 2 , reflecting in high difference of work function and modified surface band bending of TiO 2 , therefore promoting the injection of electrons from NCs to TiO 2 and reducing interfacial charges recombination. As a result, Au 18 (SG) 14 /TiO 2 shows higher hydrogen generation rate than Au 22 (SG) 18 /TiO 2 under light irradiation . This work would provide new insights into rational combination of metal NCs with semiconductor and highlights the overlooked effect of interfacial interaction behavior on light energy conversion.