Customizing Transition Metal Chalcogenide Heterostructure Photosystems toward Multifarious Photoredox Catalysis

Transition metal chalcogenides (TMCs) with a large absorption coefficient, a favorable energy level position, and abundant active sites have attracted considerable attention in heterogeneous photocatalysis. However, the photocatalytic redox activities of TMCs are hindered by rapid charge recombination, sluggish charge transport kinetics, and poor stability. Herein, a TMC-based heterostructure artificial photosystem is fabricated by a controllable cation exchange strategy under ambient conditions, wherein partial substitution of Cd²⁺ with Ag⁺ ions over a CdS substrate enables the epitaxial growth of an ultrathin Ag₂S layer on the CdS surface, ultimately giving rise to the CdS/Ag₂S heterostructures. The thus-obtained CdS/Ag₂S heterostructure demonstrated markedly enhanced photoredox catalytic activities in the anaerobic photoreduction of aromatic nitro compounds to amino derivatives and photocatalytic mineralization of organic pollutants under visible-light irradiation, far surpassing the pristine CdS counterpart, primarily owing to the applicable energy level configuration formed between CdS and Ag₂S as well as the favorable interfacial integration. The synergy facilitates spatially vectorial charge separation and substantially prolongs the charge lifetime of CdS/Ag₂S heterostructures. Our work would spark interest in exploring diverse TMC-based heterostructures via cation exchange for solar energy conversion.