Z-scheme SnC/HfS2 van der Waals heterojunction increases photocatalytic overall water splitting

Abstract Designing a direct Z-scheme system is one of the effective ways to develop a high-efficient photocatalyst. In this paper, we designed the SnC/HfS 2 heterojunction and explored its electronic structure and photocatalytic properties for water splitting based on first-principles calculations. Our results suggest that SnC/HfS 2 heterostructure is a typical direct Z-scheme heterojunction, which can effectively separate carriers and possesses strong oxidation and reduction capabilities. The valence band maximum of SnC is close to the conduction band minimum of HfS 2 , which is in favor of the recombination of inter-layer carriers. The very small interlayer band gap and appropriate built-in electric field direction make the migration of electrons and holes along the Z-path. The photo-generated electrons on SnC make the hydrogen evolution reaction happen continuously, while the photo-generated holes on HfS 2 make the oxygen evolution reaction happen continuously. The calculation of the reaction energy barrier indicates that the procedure of photocatalytic water splitting on the SnC/HfS 2 heterojunction can be spontaneous. Our results show that SnC/HfS 2 heterojunction is a potential direct Z-scheme photocatalyst for the overall decomposition of water.