Facile preparation of SnO2/NiO composites and enhancement of sensing performance to NO2

The smart sensor based on SnO2/NiO composite not only exhibits high response and excellent selectivity to NO2 at relatively low temperature, but also has outstanding stability and linear response to low concentration of NO2 (below a concentration of 1 ppm). The sensing mechanism was also discussed in detail, which is attributed to the significant increase in resistance in NO2 due to the formation of p-n heterojunction.