Fabrication And Gas Sensing Properties Of Flower-like Cluster Of ZnO Nanotubes

Zinc oxide(ZnO) is an important wide band gap semiconductor oxidematerial with hexagonal wurtzite structure. Nano-ZnO has excellent optical,electrical, photocatalytic and gas sensing properties. It has been widely usedin the fields of solar cells, transparent electrodes, photocatalytic degradationand gas sensors. The cost in the preparation of nano-ZnO thin film is lowand it can meet the requirements for integration, miniaturization andmulti-function, which makes it one of the most promising gas sensors in thefuture. However, the detection sensitivity is not high due to the small surfacearea of nano-ZnO thin film. In addition, Nano-ZnO is required to work athigh temperature, which may cause grain merging, the change of porosityand grain boundary. Thereby, the stability declines.In view of the above problems of nano-ZnO thin film, one-dimensionnanostructure, which has advantages such as large surface area, highsensitivity and low working temperature, was adopted. The main focus ofthis thesis was to deposit a layer of ZnO thin film onto the surface of gassensing components by magnetron sputtering method and fabricate theflower-like cluster of ZnO nanotubes by a two-step hydrothermal method.We characterized the microstructure of nano-ZnO thin film and tested its gassensing properties to ethanol, acetone, methanol, formaldehyde and so on.The main research content is summarized as following:1. A layer of ZnO thin film was deposited onto the surface of gassensing components by magnetron sputtering method and then theflower-like cluster of ZnO nanotubes were fabricated by a two-stephydrothermal method. Characterizations were done by scanning electronmicroscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and electron diffraction (SAED). The results showed thatflower morphology of ZnO clusters were formed with many root nanotubesspread radiation self-assembly. ZnO nanotubes exhibited hexagonalstructures and preferred to grow along [0001].2. Magnetron sputtering technology was futher used to deposit Pt andSnO2onto the surface of flower-like cluster of ZnO nanotubes which wereprepared in the early stage. Through SEM attachment-energy spectrumanalysis (EDS) and Raman characterization, successful modification of Ptand SnO2on the surface of ZnO nanotubes was confirmed.3. The gas components that grew with flower-like cluster of ZnOnanotubes were assembled, which were modified with Pt and SnO2, into thedevices and gas sensing properties to ethanol, acetone, methanol andformaldehyde were tested. The working mechanism of gas sensitivity ofZnO nanotubes was analyzed and the reasons why gas sensitivityperformance of ZnO nanotubes improved with doped Pt and SnO2dopedwere explained.