The GaAs/InS vdW heterostructure shows great potential as a solar-driven water splitting photocatalyst

The use of van der Waals (vdW) heterostructures composed of different two-dimensional (2D) materials has proven to be a highly effective strategy for developing active photocatalysts. In this study, we designed and investigated a novel GaAs/InS vdW heterostructure using a first-principles approach. Our results demonstrate that the heterostructure primarily interacts through vdW forces and exhibits remarkable structural stability at room temperature. Importantly, the electronic structure reveals a staggered (type-II) band alignment, facilitating efficient spatial separation of electrons and holes. With a direct bandgap of 1.54 eV, the heterostructure promotes effective electron excitation from the valence band to the conduction band. Analysis of interlayer coupling further reveals the existence of a built-in electric field from the InS layer to the GaAs layer, enhancing carrier separation at the interface and improving photocatalytic efficiency. Additionally, the heterostructure construction enhances electron mobility and light absorption, resulting in a remarkable solar-to-hydrogen (STH) efficiency of up to 17.06%. Overall, these findings underscore the promising potential of the heterostructure as an efficient photocatalyst for solar-driven water splitting.