A first-principles study of electronic structure and photocatalytic performance of GaN–MX2 (M = Mo, W; X= S, Se) van der Waals heterostructures

Abstract

Modeling novel van der Waals (vdW) heterostructures is an emerging field to achieve materials with exciting properties for various devices. In this paper, we report a theoretical investigation of GaN–MX₂ (M = Mo, W; X= S, Se) van der Waals heterostructures by hybrid density functional theory calculations. Our results predicted that GaN–MoS₂, GaN–MoSe₂, GaN–WS₂ and GaN–WSe₂ van der Waals heterostructures are energetically stable. Furthermore, we find that GaN–MoS₂, GaN–MoSe₂ and GaN–WSe₂ are direct semiconductors, whereas GaN–WS₂ is an indirect band gap semiconductor. Type-II band alignment is observed through PBE, PBE + SOC and HSE calculations in all heterostructures, except GaN–WSe₂ having type-I. The photocatalytic behavior of these systems, based on Bader charge analysis, work function and valence and conduction band edge potentials, shows that these heterostructures are energetically favorable for water splitting.