Atom-Precise Heteroatom Core-Tailoring of Nanoclusters for Enhanced Solar Hydrogen Generation.

While core-shell nanomaterials are highly desirable for realizing enhanced optical and catalytic properties, their synthesis with atomic-level control is challenging. Here, the synthesis and crystal structure of [Au Ag (SePh) ] , the first example of selenolated Au-Ag core-shell nanoclusters, comprising a gold icosahedron core trapped in a silver dodecahedron, which is protected by an Ag (SePh) shell, is presented. The gold core strongly modifies the overall electronic structure and induces synergistic effects, resulting in high enhancements in the stability and near-infrared-II photoluminescence. The Au Ag and its homometal analog Ag , show strong interactions with oxygen vacancies of TiO , facilitating the interfacial charge transfer for photocatalysis. Indeed, the Au Ag /TiO exhibits remarkable solar H production (6810 µmol g  h ), which is ≈6.2 and ≈37.8 times higher than that of Ag /TiO and TiO , respectively. Good stability and recyclability with minimal catalytic activity loss are additional features of Au Ag /TiO . The experimental and computational results reveal that the Au Ag acts as an efficient cocatalyst by possessing a favorable electronic structure that aligns well with the TiO bands for the enhanced separation of photoinduced charge carriers due to the relatively negatively charged Au core. These atomistic insights will motivate uncovering of the structure-catalytic activity relationships of other nanoclusters.