h2D-C₂N/C₃B Two-Dimensional Heterostructures: A Direct Z-Scheme Photocatalyst for Overall Water Splitting

A research hotspot in the clean-energy field has been the two-dimensional (2D) heterostructure (HTS)-boosted mechanisms for photocatalytic water splitting. In this work, a direct Z-scheme photocatalyst based on holey 2D C2N (h2D-C2N) and C3B composites is put forward. Through density functional theory (DFT), the band structures, partial charge density, and optical properties of h2D-C2N/C3B HTSs are explored. The band-edge locations can be effectively adjusted by strain. During the process of photocatalytic water splitting, the charge-transfer path of electrons is determined. The conduction band (CB) of h2D-C2N and the valence band (VB) of C3B maintain their respective oxidation and reduction capabilities. The composite electrons are provided by the CB of C3B, while the composite holes are provided by the VB of h2D-C2N. Based on this, h2D-C2N/C3B HTSs are determined as Z-scheme photocatalysts. Meanwhile, A-B and A-C HTSs, under specific strain, which have close to the ideal potential requirements for the HER and the OER, are predicted. Our findings suggest that h2D-C2N/C3B HTSs are promising candidates for future optoelectronic and nanoelectronic applications, which also provide a precious reference for future experimental investigations.