Fe-doped SnSe monolayer: A promising 2D material for reusable SO2 gas sensor with high sensitivity

Recently, 2D materials have attracted great interest in the gas-sensing field, in which TMMC GeS, GeSe, SnS, and SnSe monolayers have been reported as promising SO2 sensing materials [Chem. Phys. Lett. 686 (2017) 83–87; Appl. Surf. Sci. 484 (2019) 33–38]. However, the transport properties, sensitivity, and recovery times of such structures related to the adsorption of SO2 molecule have not been published to date. In this work, we found that the recovery times of the pristine GeS, GeSe, SnS, and SnSe monolayers after SO2 adsorption are too short, indicating their low application possibility for SO2 sensing materials. Interestingly, the transition metals doping (Cr, Mn, or Fe) improves the recovery time of the SnSe monolayer in respect of SO2 molecules. Especially the calculated recovery time of the Fe-doped SnSe monolayer in respect of SO2 molecules at 373 K is 27 s, which is suitable for reusable gas sensors. Moreover, we first designed an SO2 gas sensor based on the Fe-doped SnSe monolayer with two Au electrodes. The NEGF formalism-based calculations show its high sensitivity to an SO2 molecule. Our results suggest that the Fe-doped SnSe monolayer is a promising 2D material for reusable SO2 gas sensors with high sensitivity. (Left panel) A schematic of a gas sensor device designed in relation to SO2 molecules where the proposed device is structured from a doped Fe-SnSe monolayer that acts as a scattering zone with two Au electrodes at either side. The signal of the sensing device before and after absorbed SO2 molecules is relatively detected. (Right panel) The sensitivity as a function of the bias voltages applied between the given electrodes of the device is thus detected. [Display omitted] •The adsorption properties of GeS, GeSe, SnS, and SnSe monolayers with respect to SO2 molecules were systematically elucidated.•A short recovery time of the pristine GeS, GeSe, SnS, and SnSe monolayers is found.•Transition metals (Cr, Mn or Fe) doping improves the recovery time of the SnSe monolayers in respect of SO2.•The Fe-doped SnSe monolayer is a promising 2D material for reusable SO2 gas sensors.