SnS2 monolayer as a promising candidate for NO2 sensor or capturer with high selectivity and sensitivity: A first-principles study

As a common toxic gas, the sensing and capture of NO2 are two important topics closely related to human health and the environment. In this work, the adsorption behavior of a SnS2 monolayer on gas molecules including NO2, CO2, SO2, NH3, acetone, ethanol, methanol and formaldehyde was studied by DFT methods to explore its possibility as a NO2 gas sensor or capturer. Among these gases, only NO2 can be chemisorbed on to the SnS2 monolayer with an adsorption energy of −0.43 eV. Compared with other gases, the significantly altered I–V relationship of the SnS2 monolayer before and after adsorbing NO2 demonstrates that the SnS2 monolayer has superior sensitivity and selectivity for NO2. In particular, the adsorption of NO2 by the SnS2 monolayer strengthens linearly with increasing biaxial strain, while the adsorption of other gases remains weak, thus offering an effective route for the SnS2 monolayer to capture and release NO2 by adjusting the magnitude of an applied biaxial strain. These results demonstrate that the SnS2 monolayer is an excellent candidate material for the effective capture, separation, storage and detection of NO2.