Facile Synthesis And Gas Sensing Properties Of Sno₂ Nanosheets

In this dissertation, the preparation and gas sensing properties of SnO₂ nanosheets have been investigated. Pt-modified and Al/Fe-doped SnO₂ nanosheets have also been prepared to improve the gas sensitive characteristics. The main contents can be briefly described as follows:(1) Well-dispersed SnO₂ nanosheets were obtained by the reaction of SnCl2?5H2O and CO(NH2)2 using homogeneous precipitation method. The morphology, size and phase of the nanosheets were analyzed by scanning electron microscope (SEM),transmission electron microscope (TEM) and X-ray diffraction (XRD). It can be seen that well crystallized tetragonal SnO₂ nanosheets with the thickness less than 10 nm were distributed on the substrate.(2) A novel micro gas sensor based on the SnO₂ nanosheets was successfully fabricated. The gas-sensing measurement results showed that response of SnO₂ nanosheets reached 48.4 to 100 ppm ethanol and the response time was less than 8 s.(3) SnO₂ nanosheets have been modified by Pt to improve the gas sensing performance. The morphology of pure and Pt-doped SnO₂ nanosheets were analyzed by scanning electron microscope (SEM) and the content of Pt was analyzed by Energy Dispersive System (EDS). The gas-sensing properties of the sensors showed that SnO₂ nanosheets reached 14.5 to 10 ppm HCHO and formaldehyde of 0.1 ppm was detected by the Pt-doped SnO₂ micro-gas sensor.(4) Al/Fe-doped SnO₂ nanosheets were prepared by mixing SnCl2 and AlCl3/FeCl3 in aqueous solution. SnO₂ nanosheets were doped with Al /Fe in two different concentrations (1 and 2 wt.%). The morphology was found of little change and the gas sensing properties could be improved with suitable doping.(5) Al-dpoed and Pt-modified SnO₂ nanosheets were prepared and were found to be the best in gas sensing performance, both modifying and doping would help enhance the gas sensing performance.