Robust and Stable Atomically Precise Metal Nanoclusters Mediated Solar Water Splitting.

Atomically precise metal nanoclusters (NCs) represent an emerging sector of light-harvesting antennas by virtue of peculiar atomic stacking fashion, quantum confinement effect, and molecular-like discrete energy band structure. Nevertheless, precise control of charge carriers over metal NCs has yet to be achieved by the short carrier lifetime and intrinsic instability of metal NCs, which renders the complexity of metal NCs-based photosystems with photoredox mechanisms remaining elusive. Herein, fine tuning of charge migration over metal NCs is demonstrated by constructing directional charge transfer channels in multilayered heterostructure enabled by a facile layer-by-layer (LbL) assembly approach, wherein oppositely charged branched poly-ethylenimine (BPEI) and glutathione (GSH)-capped gold NCs [Au x NCs, Au 25 (GSH) 18 NCs] are alternately deposited on the metal oxide (MOs: TiO 2 , WO 3 , Fe 2 O 3 ) substrates. TheAu x (Au 25 ) NCs layer serves as light-harvesting antennas for engendering charge carriers, andBPEI interim layer uniformly intercalated at the interface of Au x NCs layer constitutes the tandem hole transport channel for motivating the charge transfer cascade, resulting in the considerably enhanced photoelectrochemical water oxidation performances. Besides, poor photo-stability of Au x NCs is surmounted by stimulating the hole transfer kinetics process.