Electronic and photocatalytic characteristics of van der Waals MoSeTe/GaSe Heterostructures

Abstract

Identifying an efficient photocatalyst is essential for tackling energy scarcity and environmental pollution. Two-dimensional (2D) materials have attracted considerable interest owing to their remarkable electronic, optical, and mechanical characteristics. They are regarded as potential alternatives to Si-based semiconductors. 2D materials exhibit significant potential as effective candidates for highly efficient photocatalysis. This results from their exceptionally high surface area and the minimal distance charge carriers must traverse. Gallium monochalcogenides (GaX where X = S, Se, Te) and Janus transition metal dichalcogenides, which consist of two different chalcogenides (S, Se, or Te) paired with a single transition metal (Mo, W, Pt, etc.), are increasingly recognized for their potential in photocatalytic water splitting. This recognition is attributed to their advantageous band gap and remarkable stability. In this present work, we study the electronic band structure, photocatalytic properties, and stability of a novel van der Waals MoSeTe/GaSe heterostructure based on first-principles calculations. The MoSeTe/GaSe heterostructure demonstrates potential as a photocatalyst for overall water splitting, attributed to the effects of the built-in electric field. The built-in electric field at the interface effectively separates photogenerated carriers. Our results reveal that the energetically stable MoSeTe/GaSe heterostructure exhibits a type-I band alignment, which promotes the spatial confinement of photogenerated electron-hole pairs a favourable feature for enhanced radiative recombination, making it suitable for optoelectronic applications. Notably, the heterostructure possesses an indirect band gap of 0.881 eV. The lattice mismatch rate is 0.68 %, and the binding energy is calculated at 7.5 meV/atom, suggesting thermodynamically favourable. The band edge encompasses the redox potential of water, suggesting that the heterostructure can facilitate hydrogen production through the photocatalytic decomposition of H₂O. The research has resulted in the development of a novel group of materials with significant potential for photocatalytic applications.