In situ XPS proved graphdiyne (CnH2n-2)-based CoFe LDH/CuI/GD double S-scheme heterojunction photocatalyst for hydrogen evolution

Graphdiyne (GD, CnH2n-2) is a two-dimensional planar network structure formed by 1, 3-diacetylene conjugated benzene ring, which has been widely explored since its first synthesis. In this study, GD was successfully prepared by cross-coupling method and applied to photocatalytic reaction. Based on morphology regulation and the construction of double S-scheme heterojunctions, the CoFe LDH/CuI/GD composite photocatalyst was prepared by coupling CoFe LDH, CuI and GD tightly. The transfer path of photogenerated carriers in CoFe LDH/CuI/GD was confirmed by in situ X-ray photoelectron spectroscopy. On the one hand, the coupling of CoFe LDH and CuI/GD effectively improves the serious aggregation of CoFe LDH nanoclusters, and improves the separation efficiency of photogenerated carriers to a certain extent. On the other hand, the construction of the double S-scheme heterojunction recombines the meaningless photogenerated charge carriers under the combined action of internal electric field, band bending and electrostatic interaction, thus retaining a large number of photogenerated electrons in the catalyst for photocatalytic reactions. Driven by visible light, the hydrogen production activity of CoFe LDH/CuI/GD (CFCG-3) can reach 8.6 times that of CuI/GD and 43.8 times that of CoFe LDH.