Adsorption and gas-sensing properties of SnO2 doped MoS2 monolayer

Selective monitoring and capture of some gases (CH4, C2H2, NO2, H2S, SO2, SO2F2, CO, H2, CO2) are helpful to discover and warn the problems such as dangerous accidents and gas pollution caused by too low or too high specific gas content. In this letter, the first-principles density functional theory (DFT) was used to calculate and analyze the geometric structure parameters of the adsorption systems composed of SnO2-MoS2 monolayer and the above gases. The electronic structure parameters and adsorption parameters such as binding energy (Eb), adsorption energy (Eads), transfer charge (ΔQ), total density of states (TDOS), energy band structure, the change rate of band gap energy (ΔEg), sensitivity (S), and recovery time (τ) were used to obtain the optimal adsorption configuration and microscopic gas sensing mechanism. The results show that the SnO2-MoS2 monolayer has strong adsorption on CH4, C2H2, and NO2 gas molecules, mainly chemical adsorption. Gas-sensitive response to other gases is relatively insensitive, mainly for weak physical adsorption. The adsorption strength of each adsorption system was CH4 > NO2 > C2H2 > H2S > SO2 > SO2F2 > CO > H2 > CO2. This letter provides a theoretical basis for the application of SnO2-MoS2 monolayer in the field of gas sensing and provides new ideas and ways for the exploration of other gas sensing materials.