Abstract: The photocatalytic performance can be significantly improved by constructing suitable heterojunction photocatalysts. It is well known that graphdiyne possesses a unique conjugated carbon network nanostructure, which gives it ample active sites on its surface and facilitates the reduction of protons. In this study, a unique new double S-scheme heterojunction photocatalyst was constructed by simple self-assembly of GDY prepared via organic synthesis methods and ZnAl-LDH. According to the study, an internal electric field controlling the transfer direction of the electron hole is formed between the interface of CuI-GDY and ZnAl-LDH, which broadens the light absorption range of the catalyst and improves the redox ability of the photocatalytic system. CuI-GDY and ZnAl-LDH are tightly bound together, which helps to separate the photogenerated carriers while preserving the strong reduction electrons in the GDY conduction band and the strong oxidation holes in the ZnAl-LDH valence band so that they can fully participate in the redox reaction. The charge-transfer paths on the S-scheme heterojunction interface were analyzed by in situ irradiation XPS. This work provides an effective strategy for the construction of double S-scheme heterojunction photocatalysts.

Key words: Conjugated carbon network, Graphdiyne, S-scheme heterojunction, Hydrogen evolution