Innovative Type-II ZnSe/InSSe heterojunction: Photocatalytic properties and strain modulation from first-principles calculations

In this study, we propose an innovative type-II ZnSe/InSSe heterojunction for efficient photocatalytic water-splitting. This heterojunction exhibits a direct band gap of 1.9 eV and staggered band alignment, which efficiently separates photogenerated carriers, facilitating overall water-splitting. The built-in electric field drives electrons to accumulate in the InSSe layer and holes accumulate in the ZnSe layer, thereby suppressing recombination and enhancing photocatalytic efficiency. The solar-to-hydrogen efficiency reaches 8.92 %. Furthermore, the electronic and optical properties of ZnSe/InSSe heterojunction can be modified by biaxial strain, with tensile strain significantly improving visible light absorption and overall efficiency. Under tensile strain, the band gap decreases, enhancing the light absorption capability in the visible range, which further boosts the photocatalytic performance. Our findings demonstrate the ZnSe/InSSe heterojunction as a promising candidate for high-efficiency photocatalytic hydrogen production, offering valuable insights for future photocatalyst development. This research provides a potential pathway to optimize semiconductor heterojunctions for sustainable energy applications through strain engineering.