First-principles design of a bifunctional InP/GaTe vdW heterostructure for high-efficiency photocatalytic and photovoltaic applications.

Developing high-performance two-dimensional (2D) photocatalysts is essential for efficient solar-driven water splitting. Here, a novel InP/GaTe van der Waals (vdW) heterostructure is investigated using first-principles density functional theory calculations. The material exhibits an indirect bandgap of 1.64 eV and thermodynamic stability at room temperature. Its type-II band alignment localizes photoexcited charge carriers on separate layers. Work function differences between GaTe and InP induce interfacial charge redistribution, generating an internal electric field from GaTe to InP that suppresses electron-hole recombination. Optical absorption reaches a maximum coefficient of 7.8 × 105 cm-1, with calculated solar-to-hydrogen and power conversion efficiencies of 29.90% and 18.61%, respectively. These dual metrics establish InP/GaTe as a versatile bifunctional platform for unassisted solar-driven water splitting and nanoscale photovoltaics, with Gibbs free-energy analysis confirming favorable reaction energetics. Collectively, these findings position InP/GaTe as a highly promising photocatalyst.