2D/2D Janus BiTeCl/GeSe vdW heterostructure as a robust high-performance S-scheme photocatalyst for water splitting

Two-dimensional (2D) S-scheme van der Waals (vdW) heterostructures (HSs) have aroused much interest as advanced photocatalysts due to their strong redox ability and light utilization. In this work, we have proposed a 2D/2D vdW HS composed of Janus BiTeCl monolayer (ML) and GeSe ML, and systematically investigated its photocatalytic performance using first-principles calculations. Our results show that the HS exhibits an appropriate electronic band in which the existence of intrinsic built-in electric field from GeSe ML to BiTeCl ML enhances the separation of photo-induced electron-hole pairs and certifies a S-scheme mechanism in the HS. Furthermore, the optical and electronic properties of the HS are nearly independent of either biaxial or uniaxial strain, showing robustness of the HS applied in an ever-changing environment. Notably, the HS can achieve spontaneously solar-driven water splitting and exhibits an enhanced solar-to-hydrogen (STH) efficiency up to 19.27 % owing to its S-scheme mechanism and wide range of light absorption with high absorption coefficient. Our results give insights to the structure, electronic and photocatalytic properties of 2D/2D Janus BiTeCl/GeSe vdW HS and may provide a promising S-scheme photocatalyst for overall water splitting.