Study On The Relationship Between The Gas Sensitivities And The Catalytic Properties Of Tin Dioxide Based Materials

Tin dioxide is widely used as a kind of popular gas-sensing material, it can be used to detect all kinds of reducing gases and flammable gases. at present, the gas sensors we can find in the market is mainly made of Tin dioxide, but for itself, the sensitivity and selectivity is not satisfied, so people have to dope or surface modify to improve it's property. On the other hand, the research of gas sensing mechanism has lagged behind the application of gas sensor, so it is difficult to guide the design and development of gas sensing material. At the same time, gas-sensing mechanism of Tin oxide is seldom reported. For the reasons above, the relationship between catalytic property and gas sensing performance has been established in this paper and the mechanism of tin dioxide has been revealed firstly.The tin dioxide powder is prepared by chemical precipitation method and the microemulsion method respectively in this paper, and the powder is treated with different oxides and noble metals as dopants. then the material is characterized by DTA-TGA, XRD and specific surface area testing. The results show that the crystallization temperature of the tin dioxide is about 500°C; the powder is pure tin dioxide nano-grain crystal; and the size of the crystal is 13nm and 67nm,the specific surface area is 42.7m² · g^-1 and 127.2m² · g^-1 respectively.The powder is made into conventional sintered side-heated sensor, and gas-sensing property to methane and alcohol is detected systematically by testing apparatus about gas-sensing testing performance. The results show the lanthanum oxide dopants or noble metal Pt. especially Pt, can increase the gas sensitivity and selectivity to ethanol, but Pd can increase the gas sensitivity to methane to more than 3, the requirement for practical application, so the improvement is meaningful. In addition, decreasing the size of the grain is useful method for improving the gas-sensing property.The catalytic property of the same materials to methane and alcohol has been evaluated systematically, the results show that the Pd can improve the catalytic property to methane, the lanthanum oxide dopants or noble metal can improve the catalytic property to ethanol distinctly, and nano-grain material has better catalytic activity.Associating the catalytic property and the sensing property, it is found that they are close...