Enhancing the NO sensing properties of the SnO2 nanowires sensors by Ar–O2 plasma modification

SnO2 nanowires were prepared in an Au-catalyzed VLS growth process by thermal evaporation. The NO sensing properties of the resistive gas sensor based on the SnO2 nanowires was found to be improved obviously after the SnO2 nanowires were treated by Ar–O2 plasma. The responses of the gas sensors to 10, 20, 30, 40, 50 ppm NO gas increased from 8.4, 10.6, 12.6, 14.2, 16.1% to 44.2, 91.9, 108.0, 118.1, 157.4% at 100 °C, respectively. The selectivity of the gas sensors to NO gas against NO2, NH3, CH4, H2 and O2 was also enhanced greatly. The characterization by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy revealed that the enhanced gas sensing properties can be attributed to the rough surfaces, the resultant dangling bond and free lattice sites, and the Sn3O4 grains appearing on the surface of the Ar–O2 plasma treated SnO2 nanowires.