| The metal oxide nanofibers?NFs?fabricated by electrospinning are very potential gas sensing materials which have large surface area,high porosity and excellent chemical/thermal stability.In this thesis,we fabricated tin oxide?SnO2?and indium oxide?In2O3?NFs respectively by electrospinning followed by high temperature calcination,and investigated their gas sensing properties.Since the response of pristine metal oxide NFs are always poor and the response/recovery rate is slow,we loaded platinum?Pt?and ZIF-67 into SnO2 and In2O3 NFs respectively,fabricated methane?CH4?sensor based on Pt-SnO2 NFs and acetone sensor based on Cobalt oxide?Co3O4?-In2O3 NFs.Firstly,we synthesized pristine SnO2 NFs by electrospinning,and fabricated SnO2 NFs film on interdigital electrodes through screen printing.It was found that the pristine SnO2 NFs had no obvious response to CH4 over a temperature range of 100-350°C.To further enhance the CH4 sensing performance of SnO2 NFs based sensors,we loaded Pt into pure SnO2 NFs and the Pt-SnO2 NFs based CH4 sensor were fabricated.Experimental results showed that the20 mol%Pt-SnO2 NFs exhibited excellent CH4 sensing properties under 100-350°C,and the optimal working temperature is 350°C.The response?Ra/Rg?for 20 mol%Pt-SnO2 NFs to1000 ppm CH4 is 4.48 and the lowest detection limit is 1 ppm.Furthermore,it could detect600-10000 ppm CH4 even at a low temperature?100°C?.We think that it is because the formation of PtO/SnO2 heterojunction and the Pt catalytic effect.We systematically investigated the CH4 sensing properties of Pt-SnO2 NFs,and comprehensively explained the CH4 sensing mechanism for the NFs,which provided new strategy to develop high performance CH4 sensors.Secondly,we fabricated pristine In2O3 NFs through electrospinning and investigated their acetone sensing properties.Then,we fabricated Co3O4-In2O3 NFs by using ZIF-67 as template and found that they exhibited more outstanding acetone sensing properties.The response?Ra/Rg?for 20 wt%Co3O4-In2O3 NFs toward 100 ppm acetone is 38.79 at the optimal working temperature of 300°C,which was about 22 times higher than that of pure In2O3 NFs.In addition,loading of Co3O4 could effectively lower the optimal working temperature of In2O3 NFs based acetone sensors and the 20 wt%Co3O4-In2O3 NFs exhibited excellent response to different concentrations of acetone at 300°C.We think that it is because the formation of Co3O4/In2O3 heterojunction and the great increasement of surface area and porosity.Furthermore,we enhanced its acetone sensing properties by loading Co3O4 into In2O3 NFs based on ZIF-67 and comprehensively explained the sensing mechanism for the NFs,which provided new strategy to develop high performance acetone sensors. |
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