Inhomogeneous oxidation of ultrathin SnS2 nanoflowers and its effect on low–temperatures NO2 gas sensing

TMDs are widely used for gas sensing because it readily interacts with gas molecules. However, excessive electrical resistance and chemical instability prone to oxidation and moisture absorption limit its versatile applications. Here, we elucidate the unique inhomogeneous oxidation process of ultrathin SnS2 nanoflowers and demonstrate the novel growth evolution pattern of oxidation generated SnO2 nanoparticles. Surprisingly, the controllable preparation of SnO2/SnS2 heterojunctions brings excellent NO2 gas sensing performance. A high response of 15.33 to 3 ppm NO2 at a low temperature operating environment of 60 °C was achieved. It was verified by DFT calculations that the SnO2 nanoparticles provide more active sites as well as generate a large amount of charge transfer with pristine SnS2, which can be responsible for the significant enhancement of gas sensing performance. Overall, this work investigates the growth pattern of SnO2 for the first time, which not only fills the research gap of SnS2 oxidation kinetics, but also provides a new idea for the efficient and stable application of SnS2–based gas sensors.