| Riassunto: | The NO gas adsorption properties of the monolayer, bilayer and trilayer MoS _2 has been studied based on the first-principles calculation. The interaction between NO and MoS _2 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 MoS _2 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 MoS _2 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 MoS _2 layers as gas sensors for important NO polluting gases in air.
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