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.