Spatially Confining Atomically Precise Metal Nanoclusters Steers Photoredox Organic Transformation

Abstract

Atomically precise metal nanoclusters (NCs) emerge as a novel class of photosensitizers, distinguished by their discrete energy band structures and abundance of catalytically active sites; however, their broader adoption in heterogeneous photocatalysis remains hindered by the challenges of ultrashort carrier lifetimes, limited stability, and the complexity of charge transport regulation. In this work, we conceptually design the metal NCs photosensitized and graphene (GR)-encapsulated transition metal chalcogenide (TMC) (GR/metal NCs/TMCs) heterostructure via a cascade electrostatic self-assembly strategy. In this multilayer ternary heterostructure, metal NCs are integrated between TMCs and GR nanosheets, which act as photosensitizers for enhancing the light absorption of TMCs and meanwhile increase the carrier density of composite photosystem. The favorable interfacial charge transport between metal NCs and TMCs along with the advantageous electron-withdrawing capability of GR simultaneously boosts charge separation over metal NCs. Benefiting from such peculiar carrier transport characteristics, the self-assembled GR/metal NCs/TMCs heterostructure demonstrates remarkably boosted and stable photoactivities toward selective photoredox organic transformation, including photocatalytic anaerobic reduction of aromatic nitro compounds to amino derivatives and photocatalytic oxidation of aromatic alcohols to aldehydes under visible light. Furthermore, the mechanisms underlying the photocatalytic processes are elucidated with clarity. Our work affords a quintessential paradigm for customizing atomically precise metal NCs in engineered photosystems aimed at converting solar energy into chemical energy.