The Adsorption behaviors of pristine MoS2 and N-MoS2 Monolayer: A First-Principles Calculation

First-principles calculations are carried out to analyze the adsorption behaviors of adatoms (H, O) and gas molecules (CO, NO2 and NH3) on pristine MoS2 and N-doped MoS2 monolayer. Compared to the H adsorption on pristine MoS2, the N doping effectively increases the H adsorption strength by shifting the most stable adsorbing site from the top of S atom to the top of N atom. But for O atom, the N doping shows ignorable influence on the adsorption behavior between the adatom and the substrate. Initially, the monolayer MoS2 is less sensitive to gas molecules CO, NH3 and NO2. After N doping, the adsorption sensitivity of N-doped MoS2 to CO changes little, but the adsorption sensitivity to NH3 and NO2 molecules is effectively enhanced as well as the adsorption energies of N-doped MoS2 with adsorbed NH3 (NO2). Moreover, the N-doped MoS2 with adsorbed CO, NH3 and NO2 always show magnetic characteristics. The migration paths and barrier energies of atom/molecules on monolayer of MoS2 and N-MoS2 are also investigated. The minimum diffusion energy barrier for NO2 on N-MoS2 is only 0.098 eV, which is lower than NO2 on monolayer MoS2 (0.273 eV). Therefore, N doping can effectively reduce the migration barrier of NO2 gas molecules on the MoS2.