Preparation Of Zinc Oxide Nanostructures And Optical, Magnetic, Optical, Catalytic Nature Study

Znic oxide is a kind of direct bandgap semiconductor whose bandgap is 3.37ev and exciton-banding energy is 60mev. According to its wide bandgap, high exciton-banding energy, fine pizoelectrical property and large specific area, nanosized ZnO has great potential application in ultraviolet lasers, optoelectronic detectors, chemical industry, medical science, environmental protection and so on. Generally, property of ZnO nanomaterial show great difference according to different fabrication method and experimental conditions. In this paper, we focused our attention on photoluminescent, photocatalytic and magnetic property of ZnO nanomaterial. By experiment and theoretical analysis, we get important conclusions as follows:1. To prepare strong visible light emitting ZnO namomaterials, we should introduce luminescent vacancies into ZnO nanocrystals. Ionic radius of Mg2+is close to Zn2+and ZnO is amphoteric compound, so we prepared Mg doped ZnO nanocrystals by co-precipitation at low temperature. Convertion of its shape, structure and photoluminescent property by Mg doping is studied. In our investigation, a direct relationship between inhanced green luminescence and Mg doping is detected. When the doping concentration achieves 20%, the quantum yield (QY) of Mg doped ZnO NCs is about 22.8%. From detections by EPR, XRD and Uv-Vis, we found Mg doping introduced VZn and IMg vacancies into ZnO nanocrystals, theoretical analysis demonstrate the inhanced visible luminescence originate from radiative transition between energy levels of the vacancies and valence band of ZnO nanocrystals.2. Magnetic property of ZnO nanocrystals varied by experimental condition, in order to investigate role of vacancies in magnetic ZnO NCs, we prepared pure and Mg/Co doped ZnO NCs and investigated magnetic property of them. The samples were prepared by co-precipitation method and annealed in air and N2. We studied variation of magnetic property of the samples with doping concentration and annealing condition. Strangely, pure and Mg dopd ZnO nanocrystals were weakly ferromagnetic but Co doped, Co/Mg co-doped ZnO nanocrystals were paramagnetic. Theoretical and experimental analysis demonstrate the ferromagnetism of pure ZnO NCs may stem from Vo vancancy, paramagnetic interaction of Co2+.ions in our samples was stronger than feeromagnetic interactions of vacancies. 3. Large surface area, less perssad on the surface is important to inhance photocatalytic property of ZnO NCs. So, we tried to prepare ZnO nanoplates by a simple combustion method and studied its photocatalytic property. The experimental results demonstrate when calcined at 600℃, the as-prepared nanoplates get better C-axis orientation and lead to bigger (0001), (0001) surface area. The as-prepared nanoplates showed good photocatalysis to methyl orange.