Research On Semiconductor Gas Sensor Based On SnO₂ And Its Composites

Gases represented by volatile organic compounds?VOCs?are threatening the safety of people's lives and property,and the sustainable development of our society.Gas sensor based on SnO₂ has been one of the research hotspots in the field of VOCs detection due to its many advantages and great development potential.In this paper,according to the research ideas of morphology control and modification of SnO₂based gas-sensitive materials,the preparation and sensing properties of SnO₂ and its composites were studied systematically.The specific research contents are listed below:1.In order to improve the utilization efficiency of SnO₂ material,SnO₂ nanorods were prepared using graphite powder as sacrifice carrier by a hydrothermal route.The dependence of the morphology of SnO₂ and their sensing properties towards C₂H₅OH on the hydrothermal reaction time was studied.It was found that when the hydrothermal time was 16h,SnO₂ presented regular and loose nanorods,with the specific surface area of 41.8m²/g.Sensors based on SnO₂ nanorods could show a high sensitivity of 10.8 to 10ppm C₂H₅OH at 260?.2.The In/Sn composite containing abundant n-In₂O₃/n-SnO₂ heterojunctions was prepared by a low-temperature precipitation route,which is convenient for industrial production.The influence of heterojunctions on the reductive activity of In/Sn composite and its interaction with target gas was investigated.The results showed that the In/Sn composite had the most abundant heterojunctions when the ratio of In³⁺was20mol%.XPS and H₂ pulse analysis indicated that adsorbed oxygen ions on the surface and reductive activity of the composite were much higher than those of SnO₂,which are conducive to the adsorption and reaction of reducing gases.The sensor based on 20 mol%In/Sn showed the highest response of about 13.2 to 20 ppm CH₃OH,as 3 times as that of SnO₂ at a working temperature of 200?.3.The low-temperature precipitation method was also used for the preparation of ZnO/SnO₂ nanoparticles,which showed a high response of 11.3 to 10ppm HCHO at a low operating temperature of 140?,while the response rate was exceptionally slow.On this basis,sensing properties of the Zn/Sn sensor towards HCHO gas at 140? were improved significantly by the catalytic effect of PdO.That is,the PdO-ZSO sensor could exhibite a high sensivity of 5.4,and rapid response?37s?and recovery?87s?towards 10ppm HCHO at 140?,showing excellent detection ability at low working temperature.