| Tin oxide(SnO2)is a typical n-type semiconductor with wide band gap of 3.6 eV.As a multifunctional material,SnO2 is the best choice of gas sensor sensing material.,due to its excellent physical and chemical properties,low cost and easy preparation.However,SnO2 also exist some disadvantages as a sensing material,such as low sensitivity,long response-recovery times,high operating temperature and poor selectivity or stability.Nanostructured SnO2 shows some advantages,including controllable and uniform morphologies,small size,lager specific surface area,et al.Using nanostructured SnO2 as sensing material of sensor,there are more adsorbed active sites on the surface of SnO2,which can improve and enhance the gas-sensing properties of sensor.In this paper,research contents mainly concentrate on the gas-sensing properties of two different structural SnO2 nanomaterials.Raspberry-like SnO2 hollow nanostructured material,one-dimensional SnO2 nanofibers and different ratio Pd-functioanlized or Cd-doped SnO2 nanofibers were prepared by using a facile hydrothermal and heat treatment process.At the same time,the gas-sensing properties of different nanostructured materials were investigated by using WS-30A gas-sensing measurement system.The main research contents and results are as following:(1)Preparation,characterization and n-butanol gas-sensing properties of raspberry-like SnO2 hollow nanostructured materialRaspberry-like SnO2 hollow nanomaterials were prepared by a facile hydrothermal method and heat treatment.Different characterization techniques,including X-ray diffraction(XRD),field emission scanning electron microscope(FESEM),transmission electron microscope(TEM),X-ray photoelectron spectroscopy(XPS)and N2 adsorption-desorption isothermal measurement,were used to analyze the crystal structure,morphology,composition,chemistry state and specific surface area of sample,respectively,and investigated the formation mechanism of samples.The gas sensor was fabricated using raspberry-like SnO2 hollow nanomaterials as sensing layer and measured the gas-sensing properties towards n-butanol.Results indicate that the sensor based on raspberry-like SnO2 nanomaterials shows high gas response toward 100 ppm n-butanol with response value of 303.49 at the optimal operating temperature of 160 ?.Moreover,the sensor exhibits good selectivity and long-term stability.Meanwhile,the gas-sensing mechanism of raspberry-like SnO2 hollow nanostructure towards n-butanol was also investigated.(2)Preparation,characterization and VOCs gas-sensing properties of one-dimensional SnO2 nanofiebrs materialsOne-dimensional SnO2 nanofibers were prepared using shaddock peels as bio-templates via a facile hydrothermal route and heat treatment.The synthesized SnO2 were characterized by XRD,FESEM,TEM,XPS and N2 adsorption-desorption isothermal measurement respectively,and discussed the formation mechanism of SnO2 nanofibers.The gas-sensing properties of sensor based on SnO2 nanofibers for various VOCs gases(including ethanol,methanol,isopropanol.acetone,formaldehyde and n-butanol)were measured.Results demonstrate that the sensor showed excellent gas-sensing properties to various VOCs gases at the optimal operating temperature of 260 ?,such as high gas response,fast response-recovery times,repeatability,long-term stability and so on.Besides,we also investigated the sensing mechanism of SnO2 nanofibers towards VOCs gases.(3)Preparation,characterization and butane gas-sensing properties of Pd-functionalized SnO2 nanofibers materialsDifferent ratio Pd-functionalized SnO2 nanofibers were prepared by using shaddock peel as bio-templates via a facile hydrothermal route and heat treatment.The gas-sensing properties of sensors based on different ratio Pd-functionalized SnO2 nanofibers toward butane gas were investigated.The results indicate that 5 mol%Pd-functionalized SnO2 nanofibers based sensor has the highest gas response value of 47.58 with 3000 ppm butane at 260 ?.What's more,the sensor showed good selectivity,fast response-recovery times and long-term stability.At the same time,the sensing mechanism of Pd-functionalized SnO2 nanofibers towards butane was also analysized.(4)Preparation,characterization and formaldehyde gas-sensing properties of Cd-doped SnO2 nanofibers materialsDifferent ratio Cd-doped SnO2 nanofibers were prepared using shaddock peels as bio-templates via hydrothermal method and heat treatment.The gas-sensing properties of sensors based on Cd-doped SnO2 nanofibers toward formaldehyde were measured.The results indicate that 5 mol%Cd-doped SnO2 nanofibers shows the highest gas response value of 51.11 with 100 ppm formaldehyde at 160 ?,and the detection limit as low as 1 ppm.Meanwhile,the sensor also showed good selectivity,repeatability and long-term stability for formaldehyde at 160 ?,and investigated the sensing mechanism of Cd-doped SnO2 nanofibers towards formaldehyde. |
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