论文部分内容阅读
本文用可控湿化学共沉淀法研制了ZnO-SnO2纳米晶体复合气敏材料并考察其对有毒气体CO和NO2的气敏性质。用TEM、BET和XRD等方法表征了纳米复合物的粒度、形貌、比表面、热稳定性和相稳定性。研究了制备的可控参数,如金属阳离子总浓度、沉淀pH值和老化时间等对复合物气敏性质的影响。研究结果表明,该纳米复合氧化物具有化学均一性,高度热稳定和相稳定性,对CO和NO2具有高的灵敏度和选择性,其气敏性质依赖于复合物组成、焙烧温度和操作温度。通过2wt%金属Cd的掺杂和10wt%Al2O3氧化物的表面包覆大大提高了气体的灵敏度和选择性。用程序升温吸脱附研究了纳米复合物表面对气体的吸脱附性能,并探讨了气敏机理。
In this paper, ZnO-SnO2 nanocrystalline composite gas-sensing materials were prepared by controlled-wet chemical coprecipitation method and their gas-sensing properties for toxic gases CO and NO2 were investigated. The size, morphology, specific surface, thermal stability and phase stability of the nanocomposites were characterized by TEM, BET and XRD. The controllable parameters of preparation, such as the total concentration of metal cations, the pH value of the precipitate and the aging time, on the gas sensing properties of the composite were investigated. The results show that the nanocomposite has chemical homogeneity, high thermal stability and phase stability. It has high sensitivity and selectivity for CO and NO2. The gas sensing properties depend on the composition, calcination temperature and operating temperature. The gas sensitivity and selectivity are greatly enhanced by the doping of 2 wt% metal Cd and the surface coating of 10 wt% Al2O3 oxide. The adsorption and desorption of gas on the surface of nanocomposites were studied by temperature programmed desorption and desorption, and the gas sensing mechanism was also discussed.