Formaldehyde Molecules Adsorption on Zn Doped Monolayer MoS₂: A First-Principles Calculation

Based on the first principles of density functional theory, the adsorption behavior of H₂CO on original monolayer MoS₂ and Zn doped monolayer MoS₂ was studied. The results show that the adsorption of H₂CO on the original monolayer MoS₂ 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 MoS₂, where the ZnMo₃ small clusters made the surface have high selectivity. The adsorption behavior of H₂CO on Zn doped monolayer MoS₂ can be divided into two situations. When the H-end of H₂CO 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 H₂CO molecule is downward, the interaction between H₂CO and the doped MoS₂ 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 MoS₂ monolayer, which can be used to detect the adsorbed H₂CO molecules. The results show that the introduction of appropriate dopant may be a feasible method to improve the performance of MoS₂ gas sensor.