Analysis Of The Gas Sensing Properties Of Modificated Precious Metal To Tin Oxide

Developing of science and technology, the environmental problems and human safely have recently arisen as one of the essential problems, which arouse public concern in our society. The importance of harmful and explosive gases detection has emerged into people’s vision and become increasingly prevalent among the scientific research. But monitoring low-concentration gas at lower working temperature is still a challenging task during the industrial processes. Miniaturized gas sensors based on metal oxide nanomaterials possess great potential as the timely detection strategy because of high sensitivity and stability, simple and cost-economy instrumentation, convenience. Tin oxide（Sn O₂） is one of great interests and has been extensively studied as an n-type semiconductor material. And tin oxide has been widely known as gas sensor material to detect reducing gases, for instance ethanol, hydrogen, CO and formaldehyde. However, the operating temperature of sensors based Sn O₂ material is comparatively higher, and the selective is relatively poorer. Hence, if some catalytic nanoparticles can be integrated into the surface of Sn O 2 nanomaterial, enhance the activity and selective can be excepted because they can accelerate the electron exchange between gas sensors and gases.（1） Choosing the Ag/Ag₂O nanoparticles decorated porous Sn O₂ microsphere for hydrogen detection. The composite with good selectivity to H2 at a relatively low working temperature（i.e. 170 °C） by using a facile impregnation method. The as obtained composites show high sensitivity, rapid response（less than 5 s） towards H2 and nearly insensitive to CO and CH4 at the same condition.（2） It is widely known that noble metal Pt, as one of the most active noble metal catalysts, can dramatically decrease the operating temperature and simultaneously improve the sensing sensitivity as well as selectivity. Prepared a formaldehyde detection of porous Pt O₂/Sn O₂ microspheres composite on the basis of the previous work. Moreover, the obtained sensor based porous Pt O₂/Sn O₂microspheres composite shows a rapid response to 100 ppb HCHO at a relatively low working temperature（i.e. 100 °C）. Meanwhile, it demonstrates a good selectivity to formaldehyde over the other reducing gases.