| Rare earth micro/nanostructured materials have been intensively studied owing to their potential application in the fields of optical, electric, magnetic, catalytic, and so on. As one of the most important rare earth oxides, CeO2 has been widely used in catalysis, fuel cells, sensor, and so on. Y2O3: Eu as a red fluorescent powder has been widely used in fluorescent lamps, field emission display device, cathode ray tube and other fields. In this thesis, a series of rare earth coordination polymers(Ln-CP) have been successfully synthesized by employing pyridine-2,5-dicarboxylate acid as ligand. Meanwhile, rare earth oxide(Ln2O3) could be obtained after thermolysis of the corresponding Ln-CP precursors. The as-prepared products were characterized by different measurement technologies. The formation mechanism and properties of the products were briefly discussed and summarized. It may provide method and experiment instruction for the synthesis of other coordination polymers and rare earth oxide. The main content of this thesis is as following:(1) Cerium-based coordination polymer hierarchical superstructures: fabrication, formation mechanism and their thermal conversion to CeO2In this work, cerium-based coordination polymer(Ce-CP) hierarchical superstructures have been successfully synthesized on a large scale employing cerium nitrate as metal salt and pyridine-2,5-dicarboxylate acid(2,5-H2PDC) as ligand by a mixed-solvothermal route. The as-obtained products were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), selected area electron diffraction(SAED), Fourier transform infrared spectroscopy(FTIR), X-ray powder diffraction(XRD), thermogravimetry(TG) analysis. As a typical micro structure,a possible formation mechanism for the hierarchical superstructures has been proposed to interpret the growth process. CeO2 with similar hierarchical structures could be obtained after thermolysis of the Ce-CP precursors at 450 oC for 4 h. The UV-vis adsorption spectrum of the obtained CeO2 shows that band gap energy(Eg) is 2.64 eV, which is lower than that of bulk ceria. Moreover, the as-obtained CeO2 could effectively degrade solution of Rhodamine B(Rh B) under UV light irradiation.(2) Facile synthesis of ceria core-shell hollow spheres with multi-shelled architecture through a template-free synthetic routeA simple and template-free approach is adopted to fabricate multi-shelled CeO2 hollow nanospheres with porous shells. The approach involves a mixed-solvothermal synthesis of the Ce-based coordination polymer nanospheres(Ce-CPs) and followed by a simple calcination treatment in air. As a typical microstructure,a possible formation mechanism of the multi-shelled architecture has been proposed. In addation, the multi-shelled CeO2 hollow nanospheres show excellent photocatalytic degradation of Rh B. Furthermore, the as-obtained multi-shelled Au-CeO2 hollow nanospheres also show eximious catalytic activity for the reduction of p-nitrophenol.(3) Y2O3:Eu hollow nanospheres: preparation and characterizationCoordination polymer nanospheres have been successfully synthesized employing pyridine-2,5-dicarboxylate acid(2,5-H2PDC) as ligand by a mixed-solvothermal route. We investigated the luminescence properties of the precursor. Y2O3:Eu hollow nanospheres were obtained after thermolysis of the precursor at 800 oC for 4 h. Compared with the precursor, the luminescent properties of Y2O3:Eu hollow nanospheres significantly enhanced. Furthermore, we also investigated the luminescent properties of Y2O3:Eu by doping different proportion of Eu. Results show that when the doping amount of Eu3+ is 5%, the luminescent intensity of Y2O3:Eu is the strongest. By contrast, it will decrease with the doping concentration Eu3+ ions increasing, even lead to the quenched phenomenon.(4) Terbium-based coordination polymer microstructures: preparation and characterization by using ultrasound, hydrothermal and microwave methodIn this paper, three kinds of terbium-based coordination polymers with similar structure have been successfully synthesized by ultrasound method, hydrothermal method and microwave method. The as-obtained products were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR), X-ray powder diffraction(XRD), thermogravimetry(TG) analysis. In addition, the luminescence properties of three samples were compared and analyzed. Results show that the luminescent intensity of sample synthesized by ultrasound method is the strongest. |
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