Effects of Adsorption of CO and NO Molecules on MoS₂/Graphene Heterostructures

Gases play a pivotal-role in controlling chemical and physical processes in environment. The adsorption of carbon-monoxide and nitric oxide on MoS₂/graphene heterostructures have been investigated using spin-polarized density functional theory - with generalized gradient approximation, incorporating van der Waals interaction. In this study, the first-principles calculations are performed to investigate - geometries, energetics of MoS₂/graphene heterostructures followed by the gaseous adsorption at different possible adsorption sites. Electronic band structures and density of states calculations suggest that the states at the Fermi level are contributed by graphene, which may increase the conductivity of the composite system. In addition, Mo-d states are observed around the Fermi level to increase total density of states in all systems. Our findings suggest that the heterostructures can physisorb these molecules and may act as useful supportive materials for gas sensing. The mechanism for these two gaseous adsorption are different with varying binding energies due to different chemical reactivity of constituent elements. In summary, our results demonstrate the possibility of using 2D van der Waals heterostructures as sensors for the detection of toxic gases.