Synthesis And Gas Sensing Properties Of Novel Porous Tin Oxide

SnO2 is an important n-type semiconductor sensing material.However,there are some drawbacks in the traditional SnO2 based gas sensors,such as high operating temperature,low gas response,long response/recovery time and poor selectivity.Optimizing the composition,structure and preparation process of SnO2 gas sensors can improve their properties.Inverse opal thin film(IOF)has a periodic ordered macroporous structure and large sueface area,which is conducive to gases diffusion and the enhancement of sensing properties.This paper described the synthetic method of Zn or In doped,Au loaded SnO2 IOF.The composition effects of SnO2 IOF on the gas sensing performance had been discussed.Moreover,effects of substrate on SnO2 IOF had also been investigated.Specific research content can be divided into the following two parts:1.1%,3%,5%and 7%(mole ratio)Zn doped SnO2 monolayer IOF were prepared on aluminium oxide(Al2O3)and SiO2/Si substrate,respectively.Research indicateed the SiO2/Si substrate was more suitable for the preparation of SnO2 IOF gas sensor.The gas sensing performance of SnO2 IOF could be improved by doping Zn,and exhibited the higher response and selectivity to ethanol.The response of the SnO2:3%Zn IOF to 100 ppm ethanol was 34,which had been enhanced 3 times higher than the pure samples.2.On the basis of the previous chapter,SnO2 IOF with 1%,3%,5%,7%In and 0.1%,0.25%,0.5%Au were prepared on SiO2/Si substrate.The response of the SnO2 IOF to 100 ppm ethanol had been enhanced from 6 to 308 by 5%In doping.Moreover,the optimum operating temperature was decreased from 350 ℃ to 250 ℃,and the response/recovery time was shortened obviously by 0.25%Au doping.The 0.25%Au-SnO2:5%In IOF based sensor exhibited high response,low operating temperature,high response speed,good selectivity and repeatability to ethanol,which has a promising application in ethanol detection.XRD and XPS characterizations had been used for discussing the mechanism of the gas sensing process.It is indicated that the doping of In and Au contributed to the increase of the adsorbed oxygen amounts,which also benefited the enhancement of the sensing performance.