NO gas adsorption properties of MoS2 from monolayer to trilayer: a first-principles study

Abstract

The NO gas adsorption properties of the monolayer, bilayer and trilayer MoS2 has been studied based on the first-principles calculation. The interaction between NO and MoS2 layers is weak physical adsorption, which is evidenced by the large distance (>3 Å), small adsorption energies (<0.9 eV) and deformation electron density. Moreover, the effect of the NO adsorption on the charge transfer and the electronic properties are also discussed. For all the NO adsorption cases, 0.04 e charge transfer exists by Mulliken/Hirshfeld analysis and and the charge density difference between NO molecular and MoS2 layers. The NO adsorption can obviously induces new impurity states at about 0.5 eV in the band gap that can lead to the change of the transport properties of the MoS2 layers and then it could detect the NO gas. We also performed semi-quantitatively theoretical analysis from the carrier concentration n and carrier mobility μ to obtain the effect of the NO adsorption on electrical conductivity. Our results provide a theoretical basis for the application of MoS2 layers as gas sensors for important NO polluting gases in air.