Giant enhancement of H2S gas response by decorating n-type SnO2 nanowires with p-type NiO nanoparticles

Metal oxide nanowires (NWs) are widely considered as promising materials for gas sensor applications. Here, we demonstrate that by decorating NiO nanoparticles on SnO2 NWs, the gas response to 10 ppm H2S increased up to ∼351-fold. The response of the NiO-decorated SnO2 NWs sensor to 10 ppm H2S at 300 °C reached ∼1372, whereas the cross-gas responses to 5 ppm NH3, 200 ppm C2H5OH, and 1 ppm NO2 were negligible (1.8 to 2.9). The enhanced H2S sensing performance was attributed by the catalytic effect of NiO and the formation of a continuous chain of n-p-n-p junctions.