Cu2Se/SeIn2S van der Waals heterostructure: A direct Z-scheme efficient photocatalyst for solar-driven overall water splitting driven by an enhanced electric field

Abstract

Two-dimensional direct Z-scheme photocatalysts, which emulate natural photosynthetic processes, have shown remarkable success in advancing hydrogen production efficiency for solar-driven water splitting. Herein, based on first-principles calculations, Cu₂Se/SIn₂S, Cu₂Se/SeIn₂S, and Cu₂Se/SeIn₂Se are predicted as efficient Z-scheme photocatalysts for solar-driven water splitting. Owing to possessing a carrier migration mechanism of Z-scheme, HER and OER occur on the Cu₂Se and XM₂Y sides of Cu₂Se/XM₂Y vdWHs respectively, with enhanced redox capabilities (HER χ(H₂) and OER χ(O₂) ranging 0.21–0.32 eV and 0.52–0.83 eV respectively). Benefiting from that the alignment of intrinsic Janus electric field (E_Janus) and interfacial electric field (E_in) enhances carrier utilization, the solar-to-hydrogen efficiencies (${\eta }_{\mathrm{S}\mathrm{T}\mathrm{H}}$${\eta }_{\mathrm{S}\mathrm{T}\mathrm{H}}$) of Cu₂Se/SeIn₂S (16.29 %) surpasses those of Cu₂Se/SIn₂S (14.35 %) and Cu₂Se/SeIn₂Se (14.77 %), all of which exceed the critical threshold for economically viable ${\eta }_{\mathrm{S}\mathrm{T}\mathrm{H}}$${\eta }_{\mathrm{S}\mathrm{T}\mathrm{H}}$ (10 %). Moreover, Gibbs free energies for intermediate reactants in HER and OER further prove their photocatalytic potentials for solar-driven overall water splitting. This work not only identified the compelling direct Z-scheme Cu₂Se/SeIn₂S for photocatalytic hydrogen production, but also deepens the understanding of the effect on E_Janus aligning to E_in which provides valuable insights for developing high-performance photocatalysts.