Study On Preparation And Gas-sensing Properties Of Nano Materials Based On SnO₂/ZnO

SnO₂,ZnO and Fe₂O₃ as a traditional metal oxide gas-sensing material,have great development in many fields.SnO₂ and ZnO are n-type wide band gap semiconductor materials and the sensitivity mechanism belongs to the surface control type,and its particle size,surface state and oxygen adsorption capacity have a very important impact on the gas sensitivity.Therefore,SnO₂/ZnO was chosen as the research content of this thesis.The main contents are :（1）Preparation and properties of Au-ZnO materialsAu-SnO₂ composites were prepared via a precipitation method.In this experiment,the percentage of Au doped were 0 at%,2 at%,4 at%,6 at% and 8 at%,respectively.The experimental results show that the nanocrystalline tin oxide crystal is prepared.When the Au doped amount is 4 at%,the sensitivity to 200 ppm acetone of the gas sensor is 64 at 300℃.When the Au doped amount is 6 at%,the sensitivity to 200 ppm ethanol of the gas sensor is128 at 240℃.（2）Preparation and properties of Au/Fe-ZnO materialsAu/Fe-doped ZnO material（Au/Fe-ZnO composite）was prepared via a low temperature precipitation method.In this experiment,the atomic percentage of Au doped was 2 at%,and the atomic percentages of Fe doped were 0 at%,5 at%,15 at%,20 at%,30 at%,respectively.The experimental results show that the nanometer zinc oxide prepared is a hexagonal wurtzite structure.When the doping amount of Fe is 0 at%,the sensitivity to 200 ppm ethanol of the gas sensor is 78 at 300℃.When the doping amount of Fe is 15 at%,the sensitivity to 200 ppm acetone of the gas sensor is 89 at 270℃.（3）Preparation and characterization of Au-ZnFe₂O₄ materialsAu-ZnFe₂O₄ composite was prepared via low temperature precipitation method.the doping amount of Au was controlled by the addition of HAuCl4 solution.The atomic percentages of Au were 0 at%,1 at%,3 at%,5 at% and 7 at%,respectively.The experimental results show that the sensitivity and selectivity of the gas sensor are not ideal.