Adsorption and gas-sensing properties of Aun (n = 1–3) cluster doped MoTe2 for NH3, NO2, and SO2 gas molecules

In this study, density functional theory calculations were adopted to investigate the adsorption of toxic gases (NH3, NO2, and SO2) on Aun (n = 1–3) doped MoTe2 monolayer. The adsorption structure, band structure, charge transfer, density of states, and molecular orbit were analyzed to better understand the interaction between the gases and the substrates. The results show that the conductivity of MoTe2 monolayer is improved after doping Au atoms. And pristine MoTe2 has poor adsorption capacity for NH3, NO2, and SO2, which belongs to physical adsorption. Compared to pristine MoTe2, the adsorption capacity of these three gases on Aun-MoTe2 is obviously improved. Moreover, Au3-MoTe2 monolayer has strong stability, and its structure hardly deforms after adsorbing gas. In addition, DOS analysis results show that Aun-MoTe2 has the strongest interaction with NO2, while the interaction with NH3 is the weakest. Molecular orbital analysis shows that the conductivity of the systems affected by gas molecules is in order of NO2 > SO2 > NH3 for Au-MoTe2 and Au2-MoTe2, and SO2 > NO2 > NH3 for Au3-MoTe2. These results provide a theoretical basis for the preparation of gas sensors based on Aun-MoTe2 used in industrial toxic gases detection.