Preparation And Acetone Gas Sensing Properties Of ZnO-based Nanomaterials

Metal-oxide semiconductors gas sensors have been attracting interest because of their ease of use, low cost, and compact size, and so on. But certain drawbacks such as low sensitivity, bad selectivity or stability the sensors have also been found. So the researchers work hard at improving these drawbacks of the metal-oxide semiconductors gas sensors. The gas properties of materials mainly depend on its structure such as surface areas, and the variety and concentration of the dopant.In this paper, hydrothermal and electrospinning was used to prepare1D ZnO nanomaterials. Both of the above methods are very esay and effective to synthetize the1D nanomaterials. And then ZnO nanomaterials were characterized with XRD、TG/DTA and FE-SEM. Then the gas sensing properties of ZnO nanomaterials doped with the element of Y by hydrothermal and electrospinning were tested in a test system. The effect of the dopant on the gas sensing properties of ZnO nanomaterials was also disscussed. Finally, the gas sensing properties of the composite ZnO/TiO2sensors were analyzed at the heating conditions.1. Pure and Y-doped (1at%,3at%, and7at%) ZnO nanorods were synthesized using a hydrothermal process. The pure ZnO had a flower-like nanostructure. The crystallography and microstructure of the synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX). With the increases of the Y content, the SEM measuring results showed that the diameter of the ZnO nanorods are increased. And comparing with pure ZnO nanorods, Y-doped ZnO exhibit improved acetone sensing properties at operating temperature400℃. The response of1at%Y-doepd ZnO nanorods to100ppm acetone was about33.2, which is larger than that of pure nanorods (about27.7). The response and recovery times of1at%Y-doped ZnO nanorods to100ppm acetone were about30s and90s, respectively. The gas sensor based on Y-doped ZnO nanorods showed good selectivity to acetone in the interfere gases of ammonia, benzene, formaldehyde, toluene, and methanol. The formation mechanism of the ZnO nanorods was briefly analyzed.2. Pure and Y-doped (3at%,6at%, and9at%) ZnO nanofibers were synthesized using the electrospinning method and characterized by XRD, FE-SEM and EDX (energy dispersive X-ray spectroscopy), respectively. It is found that Y doping does not change the morphology and crystal structures of the nanofibers. Actone sensing properties of the sensors based on the ZnO nanofibers were investigated. The acetone sensing properties of ZnO nanofibers are effectively improved by Y doping:3at%Y-doping ZnO nanofibers show a maxinum response value to acetone gas and good selectivity to acetone in the interfere gases of ammonia, formaldehyde, toluene, and methanol. The sensing mechanism was briefly discussed.3. ZnO and TiO2nanofibers were synthesized by electrospinning, respectively. They were characterized with XRD and gas sensing properties. And as-prepared ZnO and TiO2nanofibers were mixed in different molar ratio(ZnO:TiO2=1:0,1:1,5:1,10:1) to fabricate gas sensors, respectively. The gas sensing properties of the composite ZnO/TiO2sensors were analyzed. The gas sensor (ZnO:TiO2=5:1) was excellent sensitivity to acetone at the concentration of10ppm than the other gas sensor at the working temperature of400℃. And The gas sensor based on the Nanocomposites (ZnO:TiO2=5:1) showed good selectivity to acetone in the interfere gases of benzene, methanol, ammonia,formaldehyde.