Crafting Insulating\nPolymer Mediated and Atomically\nPrecise Metal Nanoclusters Photosensitized Photosystems Towards Solar\nWater Oxidization

Abstract

Atomically\nprecise metal nanoclusters (NCs) have been deemed as\na new generation of metal nanomaterials because of their characteristic\natomic stacking fashion, quantum confinement effect, and multitude\nof active sites. The discrete molecular-like energy band structure\nof metal NCs endows them with photosensitization capability for light\nharvesting and conversion. However, applications of metal NCs in photoelectrocatalysis\nare limited by the ultrafast charge recombination and unfavorable\nstability, impeding the construction of metal NC-based photosystems.\nIn this work, we elaborately crafted multilayered metal oxide (MO)/(metal\nNCs/insulating polymer)<i>_n</i> photoanodes by\na facile layer-by-layer (LbL) assembly technique. In these well-defined\nheterostructured photoanodes, glutathione (GSH)-wrapped metal NCs\n(Ag_<i>x</i>@GSH, Ag₉@GSH₆, Ag₁₆@GSH₉, and Ag₃₁@GSH₁₉) and an insulating poly(allylamine hydrochloride) (PAH) layer are\nalternately deposited on the MO substrate in a highly ordered integration\nmode. We found that photoelectrons of metal NCs can be tunneled into\nthe MO substrate via the intermediate ultrathin insulating polymer\nlayer by stimulating the tandem charge transfer route, thus facilitating\ncharge separation and boosting photoelectrochemical water oxidation\nperformances. Our work would open a new frontier for judiciously regulating\ndirectional charge transport over atomically precise metal NCs for\nsolar-to-hydrogen conversion.