Low temperature selective NO2 sensors by nanostructured fibres of ZnO

We studied the gas sensing properties of Zn nanopowders synthesised by an aerosol route. Two different powder morphologies were obtained: fibre-mats and cauliflower structure. Both sensors showed a great sensitivity against sub-ppm concentration of NO2 at low working temperature. The fibre powders relative response towards 0.4 ppm of NO2 is 50, while relative response of the cauliflower structure is 8 at 100 °C. Both sensors were also selective, since no resistance variation was observed for CO, and ethanol. On the contrary resistance variations were observed with relative humidity changes. Sensors behaviour was studied at different working temperatures in the range 20–150 °C.