The adsorption characteristics of MoS2–CuO heterojunction to polar gas molecules (CO, NO and NO2): A first–principle study

Abstract

Some polar gas molecules (CO, NO and NO2) have serious influences on the atmospheric environment and human respiratory system, so it is important to design effective gas sensors for detecting the toxic gas molecules and then removing them. In this paper, the MoS2–CuO heterojunction model was established and the potential gas adsorption sites were explored. The electronic property and the adsorption characteristics of MoS2–CuO heterojunction on CO, NO and NO2 gas molecules were calculated based on the first-principle. The results show that among them, the NO adsorption system has the highest adsorption energy (3.678 eV) and charge transfer (0.126e), with its adsorption distance of 3.088 Å. MoS2–CuO heterojunction is more sensitive to NO polar molecules than CO and NO2 gas molecules. Furthermore, the hybridization of N–2p, Cu–3d and O–2p orbits and the charge transfer in the adsorption process are revealed by the partial density of states (PDOS) and the deformation charge density (DCD). It is the main reason why the heterojunction is more sensitive to NO molecules. Therefore, MoS2–CuO heterojunction is a promising combination of gas sensor materials, which can be used for the adsorption and detection of polar molecules.