Ultra-sensitive NO2 detection based on SnS nanosheets: Experimental and DFT investigation

With the development of Internet of Things technology, gas sensors are developing towards integration and miniaturization. Therefore, developing NO2 sensors with fast response and low detection limit at low temperatures is of great significance. In this study, we report SnS nanosheets via a simple hydrothermal method with excellent NO2 sensing performance and explore its gas sensing mechanism combined with first-principles calculation. The as-prepared SnS nanosheets exhibited high response (17.6) to 50 ppm NO2, specific selectivity, and fast response/recovery time (16/35 s) at 150 °C. In addition, the theoretical limit of detecting SnS nanosheets to NO2 was 8 ppb, much lower than other NO2 gas sensors. The adsorption of SnS and SnS with oxygen defects on NO2 was analyzed by density functional theory (DFT). It was found that the excellent gas sensing performance of the SnS nanosheets was attributed to the interaction between the oxygen atoms on the surface of SnS and NO2. Our work provides a new idea for the design of a SnS-based NO2 gas sensor.