Electronic structural and photocatalytic characteristics of GeS/MoS ₂ heterostructure via biaxial and vertical strains

Abstract Inspired by the unique properties of two-dimensional (2D) materials, this work systematically investigates the electronic structure, optical absorption, and photocatalytic performance of the GeS/MoS 2 van der Waals heterostructure via first-principles calculations. We firstly confirm the excellent dynamical stability of the GeS/MoS 2 heterostructure without interfacial degradation. GeS/MoS 2 heterostructure possesses the intrinsic dipole moment-induced built-in electric field, which efficiently drives the spatial separation of photoexcited electrons and holes, with electrons localized in MoS 2 and holes in GeS. Band edge alignment analysis verifies that the GeS/MoS 2 heterostructure meets the potential requirements for full water splitting. Optical absorption calculations demonstrate that GeS/MoS 2 inherits the strong visible-to-ultraviolet light absorption capability of monolayer MoS 2 while outperforming pristine GeS in light-harvesting efficiency. Further strain engineering studies reveal that increasing the interlayer distance and applying biaxial compressive strain can effectively tune the electronic structure of the heterostructure, thus optimizing its photocatalytic activity. Collectively, GeS/MoS 2 heterostructure integrates dynamical stability, efficient carrier separation, broad-spectrum light absorption, suitable redox potential, and tunable performance, rendering it a promising candidate for solar-driven photocatalytic water splitting.