Indium Single Atoms Supported on S-Scheme Cu₃P/TiO₂ as a Photocatalyst for Hydrogen Production

Photocatalytic splitting of water for hydrogen production has great developing potentiality. However, owing to the high recombination of photogenerated electron–hole pairs, the low photocatalytic activity limits its application. Metal single atom loading is an effective method to enhance the photocatalytic activity, but further clarification of the micromechanism is needed and important. In this work, an S-scheme Cu 3 P/TiO 2 photocataly s t loaded with the In single atom (In SA ) was prepared by the photodeposition method. Irradiated by a 300 W Xe lamp, the H 2 production rate of Cu 3 P/In SA -TiO 2 reaches 8.50 mmol g –1 h –1, which is 10.6 times that of TiO 2 and 1.4 times that of Cu 3 P/TiO 2 (methanol as the scavenger). Further analysis and calculations with density functional theory suggest that the loaded In SA replace the surface Ti atoms of TiO 2 . The remarkable photocatalytic activity is ascribed to the fact that the S-scheme heterojunction greatly facilitates the separation of the photogenerated carriers, while the introduction of In SA provides a channel for the charge transport at the heterojunction interface, which further enhances the mobility and reduces the recombination of the photocarriers, thus enhancing the photocatalytic H 2 evolution property. This work provides an effective method to increase the photocatalytic H 2 production activity, as well as deepens the understanding of the activity-enhancing mechanism by loading a metal single atom.