First-principles investigations of metal (V, Nb, Ta)-doped monolayer MoS2: Structural stability, electronic properties and adsorption of gas molecules

Two-dimensional (2D) layered materials are at the forefront of research because of their unique structures and promising catalytic abilities. Here, the structural stability, electronic properties and gas adsorption of metal (V, Nb, Ta)-doped monolayer MoS 2 have been investigated by density functional theory calculations. Our results show that the metal (V, Nb, Ta)-doped monolayer MoS 2 is a stable catalyst under room temperature, due to the strong interaction between the doped metals (V, Nb, Ta) and S vacancy of monolayer MoS 2 . Compared with the gas adsorption (CO, NO 2 , H 2 O, NH 3 ) on pristine monolayer MoS 2 , doped metal (V, Nb, Ta) can significantly improve the adsorption properties, chemical activity and the sensitivity of that of adsorbed gas molecules. This effect occurs due to the strong overlap between the metal nd orbitals and gas molecule orbitals, result in activation of the adsorbed gas molecules. Analysis of Bader charge shows that, more charge transfer (−0.66 e to −0.72 e ) occur from metal (V, Nb, Ta)-doped monolayer MoS 2 to the oxidizing gas molecules (NO 2 ) acting as acceptors. While for the adsorption of CO molecules, the relative less electrons (about −0.24 e − −0.35 e ) transfer occuring from substrate to the adsorbed gases. Whereas the direction of charge transfers is reversed for the adsorption of the reducing gas (H 2 O and NH 3 ) behaving as donors, in which small electrons (0.04 e −0.09 e ) transfer from adsorbed gas to metal (V, Nb, Ta)-doped monolayer MoS 2 . Our results suggested that metal (V, Nb, Ta)-doped monolayer MoS 2 might be a good candidate for low-cost, highly active, and stable catalysts and gas sensors, providing an avenue to facilitate the design of high active MoS 2 -based two dimensional catalysts and gas sensors.