Ag₂S‑Modified ZnIn₂S₄ Nanosheets for Photocatalytic H₂ Generation

Abstract

Ag₂S was successfully\ndeposited on ZnIn₂S₄ (ZIS) nanosheets via a\nroom temperature cation exchange reaction.\nThe facile synthetic strategy allows Ag₂S to easily form\natomic-level intimate contact with ZIS nanosheets, which ensures efficient\ninterfacial charge transfer. With the optimal deposition ratio (1.10\nmol %), the hydrogen evolution rate of 25 mg Ag₂S-modified\nZIS nanosheets is 25.02 μmol h^–1, which is\n2.3 times higher than that of pristine one. It was also found that\npartial Ag₂S was reduced to metallic Ag during the photocatalytic\nreaction. On the basis of the experimental results, the photocatalytic\nreduction mechanism was discussed. Under light irradiation, metallic\nAg can rapidly capture photogenerated electrons from ZIS nanosheets\nand transfer electrons to the active sites on Ag₂S. As\na result, the synergistic effect of Ag₂S and metallic Ag\nleads to a higher photocatalytic hydrogen evolution activity. This\nwork offers an improved understanding of the reaction mechanism of\ncation exchange in ternary sulfide and provides an opportunity to\ndevelop a highly efficient photocatalyst using an Ag₂S-based\ncocatalyst.