A direct Z-scheme photocatalyst PtS2/HfGe2N4 van der Waals heterostructure for highly efficient water splitting: first-principles study†

The construction of semiconductor van der Waals (vdW) heterostructures has emerged as a promising approach to enhance the performance of photocatalysts for water splitting. In this study, a PtS₂/HfGe₂N₄ vdW heterojunction was designed, and its photocatalytic properties were investigated using first-principles calculations. The results indicate that the heterojunction exhibits strong light absorption and features a type-II band alignment. Charge transfer within the heterojunction creates an internal electric field, enabling its action as a direct Z-scheme photocatalyst. Additionally, its well-suited band edge position facilitates the redox reactions required for water splitting. Notably, the heterojunction demonstrates a high-intensity light absorption coefficient of 3.8 × 10⁵ cm⁻¹ at 2.3 eV corresponding to the green light in the visible spectrum, highlighting the heterojunction's potential for photocatalytic water splitting applications.