Enhanced CO sensing properties of Pd modified ZnO porous nanosheets

Noble metal is usually used to improve the gas sensing performance of metal oxide semiconductor (MOS) due to its better catalytic properties. In this work, we reported a synthesis of Pd/ZnO nanocomposite by an in situ reduction with ascorbic acid (AA). It was found that Pd/ZnO sensor has excellent selectivity to CO and the response of the Pd/ZnO sensor towards 100 ppm CO was as high as 15 (Ra/Rg), obviously higher than that of the pristine ZnO sensor (1.4) when the working temperature is 220 °C. Moreover, the pure ZnO sensor almost has no selectivity to CO, but the Pd/ZnO sensor has excellent selectivity to CO, which may be ascribed to the electronic sensitization of Pd. Our present results demonstrate that the Pd can significantly improve the gas-sensing performance of metal oxide semiconductor and the obtained sensor has great potential in monitoring coal mine gas.