Two-dimensional arsenene/HfNBr van der Waals heterojunction as water splitting photocatalyst: First-principles predictions

In this article, the structural stability and electronic properties of unreported arsenene/HfNBr heterostructure are systematically explored using first-principles calculation and its properties in photocatalytic water splitting are investigated. The energetic stability and thermodynamic stability of the heterojunction are verified through structural optimization and molecular dynamics analysis. The electronic structure analysis results indicate that it is a type-II van der Waals heterojunction, with an indirect bandgap of 1.68 eV. The spatial separation of photo-generated charge carriers is further enhanced under the condition of built-in electric field crossing heterojunction interface. Meanwhile, the band alignment of the heterojunction meets the requirements of photocatalytic water splitting. By applying an external electric field, its band gap can be adjusted nearly linearly by changing the electric field strength. Moreover, by applying biaxial strain, we found that the heterojunction band alignment can be effectively tuned. Under a biaxial strain of + 6 % , the heterojunction exhibits a redshift and significant improvement in its visible light absorptivity. Additionally, the Solar-to-Hydrogen efficiency is calculated to be 28.84%. Our research suggests that the arsenene/HfNBr heterostructure could serve as a viable option for photocatalytic water splitting. • An alternative way to activate 2D materials for photocatalysis is reported. • The heterostructure studied is of type II, suitable for water splitting. • Planar biaxial strain improves the visible light absorption of the heterostructure. • The system shows high robustness of the band alignment to mild electric fields.