Study On The Preparation And Properties Of Semiconducting Metal Oxides Nanostructures

Metal oxide semiconductor material with a nanostructure is a kind of important functional materials and it has been widely used in electronic devices, catalysts, energy storage and bio-engineering and other fields, which has become a hot topic in the field of nanomaterials. To date, a variety of metal oxide semiconductor material has been under intense research including ZnO, SnO₂, TiO₂, In₂O₃, Cu₂O, Fe₂O₃, Co₃O₄, WO₃ and so on. As n-type wide bandgap direct bandgap semiconductor materials, ZnO and SnO₂ has become an important role in the study of metal oxides. Therefore, ZnO and SnO₂ was selected as research content of this paper. The main contents of this paper are as follows:?1? ZnO porous microspheres were prepared by solvothermal method.Porous microspheres were prepared by simple solvothermal method with zinc acetate, glycerol and deionized water as reactant. The effects of reaction time, reaction temperature, heating rate and doping effect of cerium acetate on the product's morphology and performance were studied. With the increasing of reaction time, the surface morphology of zinc oxide microspheres changed significantly and the surface of microspheres turned from smooth to rough with a significant increase in the number of pores. The diameter of nanorods became larger with obvious six pyramid structure on the surface of their ends. The surface of the zinc oxide microspheres gradually became rough with an enhancement in the number of pores when the temperature is enhanced. And nanorods become fluffy. When heating rate is decreased, the end face of nanorods gradually produced a clear hexagonal pyramid structure and the size of the nanorods increase first and then decreases. The nanorods became smooth, indicating that the crystalline of the sample became better. UV emission peak peaks of zinc oxide microspheres showed a red shift from 385.7 nm 390.2 nm. Doping ZnO with Ce, the nanorods of the microspheres became very closely aligned. The nanorods nearly showed circular cross section, indicating the deterioration of the zinc oxide crystals. Compared with pure zinc oxide, UV emission peak of Ce-doped zinc oxide showed redshift and lower intensities. The sensing performance of Ce-doped zinc oxide microspheres is superior to pure zinc oxide. The Ce doped ZnO microspheres with Ce concentration of 6 at% exhibits high sensitivity and good selectivity.?2? The preparation of tin oxide materials and the study of its properties.Precipitation method was used to synthesize tin oxide materials and the samples were characterized by XRD and PL. Its gas sensing performance for ethanol gas and carbon monoxide was analyzed. The Pt-doped SnO₂ was prepared with protective atmosphere conditions. In the visible region, the emission intensity of Pt doped SnO₂ is significantly lower than undoped samples. The gas sensors based on Pt doped SnO₂ with doping amount of 0.7 at% showed lower optimum operating temperature?200 ?? than gas sensors based on pure SnO₂ to 50 ppm ethanol?240 ??. Precipitation method was adoped to prepare Pd-doped SnO₂ which showed the high sensitivity to different concentrations of ethanol gas and good response and recovery performance. Its response time and recovery time to 5 ppm ethanol gas are 8 s and 21 s, respectively.