A first-principles study of electronic structure and photocatalytic performance of GaN–MX(2) (M = Mo, W; X= S, Se) van der Waals heterostructures

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–MX(2) (M = Mo, W; X= S, Se) van der Waals heterostructures by hybrid density functional theory calculations. Our results predicted that GaN–MoS(2), GaN–MoSe(2), GaN–WS(2) and GaN–WSe(2) van der Waals heterostructures are energetically stable. Furthermore, we find that GaN–MoS(2), GaN–MoSe(2) and GaN–WSe(2) are direct semiconductors, whereas GaN–WS(2) is an indirect band gap semiconductor. Type-II band alignment is observed through PBE, PBE + SOC and HSE calculations in all heterostructures, except GaN–WSe(2) 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.