The Fabrication And Gas Sensing Performance Of Semiconductor Metal Oxide Produced Using Template Method

With the rapid progress and development of China's modern society and economy,and the rapid advancement of science and technology,people's safety requirements for living and working environment are becoming higher and higher,so gas sensor technology also needs to be further improved.In recent years,semiconductor metal oxide gas sensors have become a hot gas sensor for research because of their excellent performance and various potential applications,but their sensitivity and selectivity to gas need to be further improved.Since the semiconductor metal oxide gas sensors belong to the surface resistance control type gas sensing element,the gas sensing performance can be effectively improved by increasing the specific surface area.Therefore,in this paper,gas sensing materials of different semiconductor metal oxide(In2O3,SnO2,ZnO)were prepared by using biological template method and hydrothermal method,and on this basis,different metal ion doping modification were used to explore their gas sensing performance,the specific research is as follows:1.First,using In(NO3)3·4.5H2O as a raw material and yeast as a biological template,In2O3 mesoporous microspheres were synthesized by a simple method.The size of the prepared In2O3 microspheres was about 3±0.5 ?m,and the grain size was about 10±0.5 nm.The microspheres had a mesoporous structure(pore diameter 24.5 nm)and a high specific surface area(72.3 m2/g).It showed that the response of In2O3 microsphere sensor to 300 ppm n-butanol at 350? was 36;secondly,SnCl4·5H2O was used as raw material,silk was used as biological template,and SnO2 hollow fiber was synthesized by hydrothermal method.SnO2 fiber had a high surface area(102.18 m2/g)and a hollow structure(pore diameter 5.6 nm),and the fiber was composed of nano-scale SnO2 particles with a size of approximately 7±0.5 nm.SnO2 fiber had fast response to n-butanol,good selectivity and good stability.Compared with pure SnO2 material,its gas-sensitivity to n-butanol was significantly enhanced.The gas response to 300 ppm n-butanol at 200? was 435;finally,using Zn(NO3)·6H2O and In(NO3)3·4.5H2O as raw materials,using dopamine as a template,ZnO/In2O3 nanospheres were prepared by hydrothermal method.The gas-sensing results show that the ZnO nanospheres prepared by using dopamine template have fast response to n-butanol,and it had good selectivity and good stability.The response to 300 ppm n-butanol gas at 350? was 99.073.The gas-sensing performance of In2O3 nanospheres was more general.2.Based on the structural research work,we used yeast and silk as biological template materials,the effects of doping Cr on the gas sensing performance of In2O3 mesoporous materials and the influence of doping Au on the gas sensing performance of SnO2 hollow fiber were investigated.First,Cr-doped In2O3 mesoporous microspheres prepared with yeast as a biological template,the specific surface area increased to 113.8 m2/g.In terms of gas sensing performance,Cr doping can significantly improve the selectivity to acetone gas.When the doping amount of Cr3+was 0.5 mol%,its sensitivity to acetone was 2 times,4 times,8 times and 40 times that of ethanol,methanol,acetic acid and ammonia,respectively.The response of the Cr-doped In2O3 sensor to 300 ppm acetone at the optimal operating temperature of 350? was 54,which was 7 times that of the pure In2O3 microsphere sensor;secondly,the Au-modified SnO2 hollow fiber prepared with silk as a biological template had a higher specific surface area(168.66 m2/g)and a mesoporous structure(pore diameter about 9.5 nm).Gas-sensitivity testing showed that Au-modified SnO2 fiber had stronger sensing performance and faster response speed to n-butanol,and the response to 300 ppm n-butanol at 340? was as high as 667,and its response/recovery time was only 30 s/60 s3.By using.Zn(NO3)·6H2O as raw material,using different surfactants,hydrothermal method was used to synthesize ZnO materials with different morphologies.From its microscopic morphology,there were many types of ZnO morphologies,such as ZnO rods,ZnO flakes,and ZnO nanoparticles.In the gas sensitivity test,the ZnO materials prepared by CTAB and PVA had good selectivity to n-butanol.The former had a response of 300 ppm n-butanol of 45 at 300?of 45,and the latter had a response of 300 ppm n-butanol of 36 at 350 ?.