Energy band engineering over phosphorus-doped CdS/graphdiyne S-scheme heterojunction for enhance photocatalytic hydrogen production

Abstract

The high recombination rate of photoelectron-hole pairs and the limited REDOX capacity of a single photocatalyst restrict the broader application of photocatalytic water splitting for hydrogen generation. This necessitates the design of an efficient multicomponent photocatalyst. In this work, phosphate-doped cadmium sulfide (CP) was designed by energy band engineering to have a wider band gap and reduce the recombination rate of photogenerated electrons and holes. Graphdiyne, prepared through a straightforward ball milling method, exhibits high conductivity and specific surface area. It pairs well with CP morphologically, effectively reducing CP aggregation and exposing more active sites. Compared with the original CdS (CS), the changes in the conduction and valence band positions of CP can form S-scheme heterojunction with graphdiyne, which effectively improves the interfacial charge migration effect, improves the photogenerated carrier separation efficiency, and maintains a high reduction capacity. Additionally, the mechanism of photocatalytic hydrogen evolution was verified by in-situ XPS. This work provides a feasible scheme for the design and construction of graphdiyne in heterojunction photocatalyst.