Studies On Preparation, Characterization And Performance Of 3D ZnO And ZnO/TiO₂ Composite Micro/Nanostructures

3D sea urchin-like ZnO, different 3D ZnO and 3D sea urchin-like ZnO/TiO₂ micro/nanosturctures were fabricated by hydrothermal method, soft template method and electrochemical deposition method. We studied on different experimental parameters had influences on 3D topography while putting forward the possible formation mechanisms of 3D ZnO micro/nanostructures and 3D sea urchin-like ZnO/TiO₂ micro/nanostructures. Main results for these studies are as follows:?1? Sea urchin-like zinc oxide?ZnO? micro/nanostructural materials were fabricated via a new simple soft template method. In the single ammonia system, the template was H₂ gas bubbles generated by NaBH₄. We mainly discussed the dosage of NaBH₄ and reaction temperature influence on morphologies of ZnO. The results demonstrated that the optimum dosage of NaBH₄ is 48 mmol, the optimum reaction temperature is 120 ?. In addition, comparing with other template methods, this method is simple and prone to control operations. What is more it can effectively solve the problems like removing the impurities introduced and the templates and so on. The as-prepared ZnO showed preferable photoelectric properties as the anode of dye-sensitized solar cells?DSSCs?. Moreover, a new multistep growth process about how to form such a structure was proposed.?2? Three different morphological ZnO micro-nanostructures were synthesised with different adjuvants by hydrothermal method. There were the nanoneedle-assembled flower-like ZnO, the nanorod-assembled 3D urchin-like ZnO and the nanosheet-assembled 3D spherical-structured ZnO micro/nanostructures. We report the effect of different adjuvant environment on the growth of ZnO nanocrystals in search of an appropriate adjuvant-controlled synthesis of 3D crystalline ZnO. When these ZnO micro/nanostructures were used as photoanodes for dye-sensitised solar cells, their photoelectric conversion efficiency was enhanced to different degrees. The highest efficiency was that of the nanorod-assembled 3D urchin-like ZnO micro/nanostructures which is 2.37%.?3? The 3D sea urchin-like ZnO/TiO₂ composite micro/nanostructures were synthesized via an electrochemical method. The influences of reaction temperature and TiO₂:ZnO on the topography were discussed. The results demonstrated that the optimum reaction temperature is 120 ?, the optimum TiO₂:ZnO is 2:1. According to the electrostatic attraction theory, we put forward the possible formation mechanism of 3D sea urchin-like ZnO/TiO₂ micro/nanostructures. Meanwhile, the photoelectric property of this structure was studied that the short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency were 7.08 m A/cm2, 0.765 V, 0.516 and 2.79%. Its photoelectric conversion efficiency increased by 17.7% compared with that of the sea urchin-like ZnO micro/nanosturctures.