The Preparation Of Noble Metals Doping SnO₂ Hollow Nanospheres And Detection Of Gas Sensing Properties

With the environmental issues are increasingly prominent, the real-time monitoring of toxic or harmful gases in all fields helps to reduce hidden danger. At present, gas sensor is the major method of detection of toxic and harmful gases. The metal oxide semiconductor has been the most widely used as sensitive materials. In order to better meet the requirement of the social development, the research and development about high performance of gas sensor have become a research hotspot in the sensor field now. The modification research of sensitive material is the main way to improve the performance of gas sensor. A large number of studies have shown that gas sensitive materials with different morphology structure have different sensitive properties and the noble metal surface modification can effectively improve the sensitive properties of gas sensitive materials.SnO2 hollow nanospheres have been prepared via hydrothermal method by using silica nanospheres as templates. Then we loaded Pd in the SnO2 nanospheres through impregnation-precipitation method. The structures and morphology of the sensitive materials after dopping were characterized by XRD, TEM, EDS, and XPS. The results show that gas sensitive materials are PdO/SnO2 hollow nanospheres, palladium in the gas sensitive material exists as palladium oxide and the morphology did not change significantly after doping. In addition, we have tested the sensitive performance of the PdO/SnO2 and found the “spillover effect” of PdO particles. From the test, we conclude that the optimum operating temperature and the optimum doping ratio are 150 °C and 1 mol%, respectively. Moreover, 1 mol% PdO/SnO2 exhibits a good sensitivity and selectivity for CO detecting at 150 °C.Furthermore, we have also prepared Au doping SnO2 hollow nanospheres through impregnation-precipitation method and added the sodium borohydride solution to reduce the gold ions to metallic gold. The characterization results of the materials’ structure and morphology show that the gas sensitive materials are Au/SnO2 hollow nanospheres and the morphology does not change after doping. We have tested the sensitive response of Au/SnO2 for the detection of ethanol, methanol, formaldehyde and toluene. And the responses of Au/SnO2 to 200 ppm ethanol, methanol, formaldehyde and toluene are 4.8, 8, 7, and 66 at 225 °C, respectively. Besides, the responses of Au/SnO2 to 1 and 5 ppm ethanol are 2 and 6.8, respectively. These results fully illustrate that Au/SnO2 hollow nanospheres exhibit an excellent sensitivity and selectivity for ethanol under 225 °C.