Investigation On Gas Sensor Based On SnO₂Micro/Nanostructured Materials

Metal oxide semiconductor gas sensor technology is a hot research topic in thefield of the sensor in recent years. Gas sensor technology has been widely used due toits high sensitivity, low energy, simplicity and the portable characteristics. Tin oxide isone of the earliest and the most common gas sensitive material, due to its stablephysical and chemical properties and excellent electric conductivity. Gas sensors basedon SnO2micro/nanomaterials possess high sensitivity, long life, good stability,corrosion resistance, etc. This thesis is based on tin dioxide micro/nano materialpreparation, to improve gas sensitive performance and extending the application of gassensor.The main research results are as follow:AgCl-SnO2nanocomposites were fabricated by one step hydrothermal method.The as-synthesized product was characterized using scanning electron microscope(SEM), transmission electron microscope (TEM), and X-ray powder diffraction (XRD).Gas sensor was prepared and tested for the detection of volatile organic compounds(VOCs), such as ethanol,2-chloroethanol, and acetone et al. The results show thatAgCl-SnO2nanocomposites exhibit excellent sensing performances towards VOCs.Porous SnO2structures are successfully obtained through a hydrothermal methodusing SnCl4.5H2O as tin source and water as the solvent. Ag nanoparticles (NPs)decorated porous SnO2structures have also been prepared by the impregnation method.The as-synthesized nanostructures with the diameters ranging from4-5μm arecomposed of porous nanosheets with the average thickness of60nm. The gas sensingproperties of Ag NPs decorated porous SnO2structures for ECH gas were investigatedin detail, and the results showed that the10%Ag NPs decorated porous SnO2MFs gassensor was the optimum sensor, demonstrating response (S=50) for100ppm ECH gas,while the working temperature was decreased by about180oC. In addition, it showed alow detection level (0.5ppm) for ECH gas, and good reproducibility and repeatability,and long-term stability, implying promising application in detecting ECH gas.A gas sensor based on SnO2@SnO2yolk-shell nanospheres were successfully synthesized usinga template method. The as-prepared yolk-shell nanospheres exhibit a good response to acetone gas and1-butanol gas. The detection limit (Ra/Rg) of the fabricated sensor was1.35for acetone gas of50ppb, and1.23for1-butanol gas of100ppb. Relative humility was weak effect to gas sensingdetection, indicated the sensors was suited to detect exhaled breath for lung cancer patients.