Enhanced Sub-ppm NO₂-Sensing Properties of SnS₂ Sheet Flowers Decorated With Au Nanoparticles at Near Room Temperature

Tin(IV) sulfide (SnS2) decorated by different levels of Au nanoparticles was successfully prepared by the solvothermal method, followed by in situ reductions. The Au nanoparticles were uniformly coated on the surface of SnS2 sheet flowers. Further gas-sensing test results show that the modified Au nanoparticles greatly enhanced the NO2-sensing performances of SnS2 sheet flowers. In particular, the sensor based on 0.5 wt% Au-SnS2 exhibited a high response of 13.2 toward 2 ppm NO2, which was 10.047-fold higher than that of the pristine SnS2 sensor at near room temperature (60 °C). Meanwhile, it also shows a curtate response and recovery time (45/148 s) and improved selectivity toward NO2 in comparison with pristine SnS2. The enhanced sensing mechanism of composites was probably due to the electronic and chemical sensitization of Au nanoparticles. The sensor based on 0.5 wt% Au-SnS2 presents huge advantages in detecting low-concentration NO2 at near room temperature.