Formaldehyde Molecules Adsorption on Zn Doped Monolayer MoS: A First-Principles Calculation.

Based on the first principles of density functional theory, the adsorption behavior of HCO on original monolayer MoS and Zn doped monolayer MoS was studied. The results show that the adsorption of HCO on the original monolayer MoS is very weak, and the electronic structure of the substrate changes little after adsorption. A new kind of surface single cluster catalyst was formed after Zn doped monolayer MoS, where the ZnMo small clusters made the surface have high selectivity. The adsorption behavior of HCO on Zn doped monolayer MoS can be divided into two situations. When the H-end of HCO molecule in the adsorption structure is downward, the adsorption energy is only 0.11 and 0.15 eV and the electronic structure of adsorbed substrate changes smaller. When the O-end of HCO molecule is downward, the interaction between HCO and the doped MoS is strong leading to the chemical adsorption with the adsorption energy of 0.80 and 0.98 eV. For the O-end-down structure, the adsorption obviously introduces new impurity states into the band gap or results in the redistribution of the original impurity states. All of these may lead to the change of the chemical properties of the doped MoS monolayer, which can be used to detect the adsorbed HCO molecules. The results show that the introduction of appropriate dopant may be a feasible method to improve the performance of MoS gas sensor.