Probing the Advantageous Photosensitization Effect of Metal Nanoclusters over Plasmonic Metal Nanocrystals in Photoelectrochemical Water Splitting

Atomically precise metal nanoclusters (NCs)-based photocatalytic systems have garnered enormous attention owing to the fascinating merits including unique physicochemical properties, quantum confinement effect, and photosensitization effect, which are distinct from conventional metal nanocrystals (NYs). Nevertheless, a systematic comparison between electrons photoexcited from metal NCs and hot electrons from surface plasmonic resonance (SPR) effect of metal NYs in boosting photoelectrochemical water splitting reaction remains blank. Here, we report the strict and comprehensive comparison on the capability of electrons photoexcited from glutathione-capped gold nanoclusters (Au_x@GSH) and hot electrons from plasmonic excitation of gold nanoparticles (Au NYs) self-transformed from Au_x@GSH to trigger the photoelectrochemical (PEC) water splitting reaction under visible light irradiation. The results indicate that photoelectrons of Au_x NCs trigger a more efficient charge transport rate than hot electrons of plasmonic Au NYs in terms of light-harvesting and conversion efficiency under identical conditions. Moreover, charge transfer characteristics in Au_x NC- and Au NY-based PEC systems were established. This work would reinforce our deep understanding of these two pivotal sectors of metal nanomaterials for solar energy conversion.