Preparation Of Sensitized Photocatalyst Based Quantum Dots And Its Photocatalytic Performance

Nowadays, photocatalytic technology is increasingly focused on by researchers all over the world for its advantages of no secondary pollution, good performance in treatment. However, for UV content accounts for about 5% of total in sunlight, TiO2, ZnO as the frequently used UV semiconductor photocatalyst that both of them have the defect of the low utilization rate of visible light which obstacles to the development in catalysis of visible-light. Hence, a growing amount of researchers take notice of improve the utilization ratio of sunlight by the methods such as construction of porous structure, sensitization effect of semiconductor. TiO2, ZnO are choosen as the research objectives in the thesis, through the way of composite narrowband semiconductor CdTe quantum dots to receive the compound photocatalyst. The ability of photocatalytic for these composite catalysts are evaluated using the remove rate of Rhodamin B(RhB), the performance of sterilization of Escherichia coli(E.coli), and the following two main points are focused on.(1) PEG was used as the pore forming agent to prepare the porous TiO2 by the of sol-gel. Under the experiment condition of ultrasound, CdTe QDs were directly synthesized on the surface of porous TiO2. The result that N2 adsorption desorption corresponded to the feature of type-IV isotherms which explained the sample had the porous structure. The aperture of the as-prepared sample was about 5nm via the distribution of the pore size. The XRD, TEM showed that on the surface of TiO2, CdTe QDs had been observed. The results of photocatalysis showed that CdTe/TiO2 was better than porous TiO2, the performance of photocatalysis could obviously enhanced explaining that construction of porous, sensitization effect of CdTe QDs.(2) As the effect with different quantity of Na OH, ZnO powder was prepared directly used hydrothermal method with different time in 80℃, with the Zn resource of Zn(OAc)2, obtaining composite material(hydrothermal time=2, 4, 6, 8, 10). The result of XRD showed that as-prepared ZnO samples were fully consistent with the standard of position of peaks and the peaks of Cd Te could be observed in the spetrum as well. Among them, the sample which used 4g NaOH had the best crystallinity, When the hydrothermal time was 8h showed the best performance. Photocatalysis under visible light analysis indicated that the reaction rate of 8h was 3.3 times than pure ZnO. TEM results showed that morphology of ZnO was nanorod which had the diameter of 200 nm, as the result of SEM showed ZnO had the morphology of sea urchin. DRS analysis stated that nanocomposite had the distinct enhancement for visible-light absorption. PL spectra truly showed that the ultraviolet emission peak was lower, with comparing to the pure ZnO, which illustrated the lower electron-hole recombination ratio. Meanwhile, bactericidial activity was improved obviously with the sensitization of CdTe QDs.