The investigation of electronic and photocatalytic characteristics of van der Waals WSeTe/GaSe heterostructures: the frist principles study

Abstract

The development of efficient photocatalysts is essential to addressing global energy demands and mitigating environmental degradation. Two-dimensional (2D) materials have emerged as promising candidates for photocatalytic applications due to their large surface area, tunable band structures, and short charge carrier diffusion lengths. Among them, group-III monochalcogenides and Janus transition metal dichalcogenides (TMDs) have garnered significant interest for solar-driven water splitting, owing to their suitable band edge positions and inherent structural asymmetry. In this work, we propose a novel van der Waals (vdW) heterostructure composed of WSeTe and GaSe monolayers, systematically investigated via first-principles calculations. The heterostructure demonstrates thermodynamic stability, with a low lattice mismatch of 0.47% and a binding energy of -8.6 meV/atom. Electronic structure analysis reveals a type-I band alignment and a direct band gap of 0.849 eV. Notably, the built-in electric field at the interface promotes spatial separation of photoexcited carriers, reducing recombination losses. The conduction and valence band edges of the WSeTe/GaSe heterostructure straddle the water redox potentials, confirming its viability for overall photocatalytic water splitting under neutral conditions. In addition, the strong light absorption in the visible spectrum, coupled with favorable charge transport properties, enhances its potential for integrated optoelectronic and energy conversion systems. This study offers fundamental insights into the interfacial physics of 2D Janus-based heterostructures and presents WSeTe/GaSe as a promising platform for next-generation photocatalysis.