Adsorption and Gas Sensing Properties of h-BN/WS2 Heterojunction for Toxic Gases: A DFT Study

Tungsten disulfide (WS2) and hexagonal boron nitride (h-BN) monolayer, and h-BN/WS2 heterojunction with low lattice mis-match is constructed using density functional theory (DFT). The band structures, density of states (DOS), charge density differ-ences (CDD), work function (WF), adsorption energy and adsorption distance of h-BN/WS2 heterojunction for six gases molecules (CO, CO2, NO, NO2, SO2, and H2S) are systematically discussed. Gas adsorption on one-side and both-sides of the heterojunction is considered. The results indicate that the band gap of the heterojunction is lower than that of h-BN and WS2, indicating that the construction of heterojunction is beneficial for conductivity. For six gases, the adsorption energy of one-sided adsorption is significantly greater than that of both-sided adsorption, except for CO2 and NO. The adsorption of NO and NO2 introduces the magnetism into the system. Interestingly, the h-BN/WS2 heterojunction demonstrates excellent selectivity for NO gas under one- sided and both-sided adsorption. The corresponding adsorption mechanism is explored