Synthesis And Performance Of Rare Earth-doped Composites Materials

ZnO, as an important industrial material, has a comprehensive application in optics, electricity, magnetics, and is becoming focus of research. In addition, ZnO has attracted much attention with respect to the heterogeneous photocatalysis due to stability, nontoxic and with strong oxidizing power. The results of research have indicated that ZnO has excellent activity in the photocatalytic oxidation of different organic compounds, which is recognized as a promising application in the degradation and complete mineralization of environmental pollutant. However, a few drawback of using ZnO as photocatalyst limits its commercial application. For example, it can only be activated by ultraviolet light of wavelength below 385 nm. The ultraviolet light reaching the earth's surface is less than 5% of the solar energy, which is too low to attain significant photodegradation in commercial application. The other main reason is recombination of photo-generated electrons and holes, whith remarkably reduces photodegradation efficiency.In this thesis, in order to improve the photocatalytic activity of ZnO, Eu(III) was doped into matix of nano-ZnO to gain composite photocatalyst by codeposition method. The result indicated doping of little Eu(III) could not change wurtzite structure of nano-ZnO, but had influence surface morphology of the photocatalyst. The composite photocatalyst has littler grain size and better dispersion compared with pure ZnO calcined at the same temperature. In photocatalytic degradation experiment of methylene blue, it was found that doping of little Eu(III) improved photocatalytic degradation activity of nano-ZnO and the photocatalyst with 1.5% doping content and calcined at 450℃exhibited the best performance in all products.A Eu(III)-doped ZnO composite photocatalyst was synthesized by codeposition coupled with ultrasonic. It was found that the catalyst had higher photocatalytic activity than that obtained in convenient water bath condition.Composite photocatalysts Gd-doped ZnO with different doping content was synthesized by similar method and characterized with SEM and XRD. Influences of doping content and calcining temperature on surface morphology of photocatalyst ware investigated. It is shown that the photocatalytic activity of ZnO to the degradation reaction of methylene blue was effectively enhanced by doping Gd3+ ion. The composite photocatalyst Gd/ZnO powder with 1.5 % doping content and calcined at 500℃exhibited the most excellent photocatalytic activity. Besides, the mechanism of the improvement of the photocatalytic activity of ZnO was also discussed briefly.Finally, Eu(DBM)3Phen/PMMA composite films with different molecular weight of PMMA were successfully synthesized by incorporating the complex Eu(DBM)3Phen into PMMA made by plasma polymerization method. The effect of PMMA on the fluorescence properties of Eu(DBM)3Phen complex was investigated. The results indicated that Eu(DBM)3Phen complex was homogeneously dispersed in PMMA films, which led to a remarkable increase of the fluorescence intensity of polymeric films. The fluorescence intensity of the luminescent membrane increases with increasing of the molecular weight of PMMA polymer.