Theoretical Design of an InSe/GaTe vdW Heterobilayer: A Potential Visible-Light Photocatalyst for Water Splitting

Using first-principles calculations, we show that a two-dimensional van der Waals (vdW) InSe/GaTe heterobilayer (HBL) can serve as a potential visible-light-driven photocatalyst for water splitting to produce hydrogen, which notably improves the photocatalytic performance over that of isolated InSe and GaTe monolayers. The type-II band alignment and high carrier mobility of the InSe/GaTe HBL facilitate the spatial separation of photogenerated carriers and thus enhance the photocatalytic efficiency. Meanwhile, the separate absorption of H⁺ and OH^– on the surfaces of InSe/GaTe HBL is beneficial to the photocatalytic redox reactions. Moreover, InSe/GaTe HBL can significantly extend the range of light harvesting from visible light to infrared light. The predicted maximum power conversion efficiency achieved is 12.3%. These results indicate the InSe/GaTe HBL is a promising photocatalyst for water splitting.