Structural, electronic and adsorption properties of monolayer 2H-MoS₂ on graphene substrates: A computational study

Two-dimensional molybdenum disulfide (MoS₂) is a prospective material for gas sensing applications. Charge transfer between adsorbed gas and monolayer MoS₂ is known to be a central mechanism responsible for the gas detection. This paper seeks to address the influence of underlying substrate, which is relatively less studied. The atomic and electronic structures and adsorption properties of monolayer 2H-MoS₂ in MoS₂/graphene heterostructures, with comparisons to the case of freestanding MoS₂, are investigated using first-principles density functional theory calculations. The effect of the underlying graphene layer on the adsorption of NH₃ and NO₂ on monolayer 2H-MoS₂ is found to be insignificant. However, our simulations demonstrate that monolayer MoS₂ can be significantly corrugated when it adheres to a rippled graphene substrate. This may result in a substantial modification of the MoS₂ electronic structure and thus exert influence on its gas sensing performance.