Selective detection of propanol vapour at low operating temperature utilizing ZnO nanostructures

Abstract

We report on the propanol vapour (C3H8O) gas sensing characteristics of ZnO nanostructures prepared via hydrothermal assisted method. The ZnO-4h sensor showed a high response (i.e. resistance ratio), sensitivity and selectivity toward C3H8O gas at low operating temperature of 125 °C. A response and recovery times of approximately 190 and 200 s were recorded. The response of ZnO-4h based sensor to 40 ppm C3H8O was approximately 2 times higher than that of other sensing materials in dry air, while in the presence of 40% RH the response was 5 times higher. The exceptional C3H8O-sensing performance of ZnO-4h is related to more C3H8O adsorption sites provided by VO. The ZnO-04h based sensor showed a clear repeatability towards 40 ppm C3H8O for four successive cycles in the presence of various RH of 40 and 60% at 125 °C. The sensor response improved in the presence of RH humidity showing that the water vapour was not competing with the C3H8O for the pre-adsorbed oxygen ions, thus its interfering effect in the C3H8O sensing was considerably minimized. The ZnO-4h based sensor was further tested for long-term stability and the sensor was very stable after 45 days. The fundamental sensing mechanism towards C3H8O vapour is also discussed.