Study On Multifunctional Hybrid Rare Earth Luminescent Materials Preparation And Properties

Luminescent rare earth complexes has attracted considerable attention because of their characteristic luminescence properties. However, these complexes still have disadvantages in thermal stability and mechanical stability. In order to overcome these shortcomings, the rare earth complexes can be incorporated into inorganic matrices to improve their stabilities. Then the new marerials will combine the lanthanide luminescent complexes with inorganic matrices. Recently, people hope to find a kind of material that posseses multifunctional properties then have several different components for assembly to form new material with multiplefunctions. In this paper, we combined the luminescence of rare-earth materials with the electrochemical and catalysis property of nobel nanoparticles, and prepared the bifunctional nanomaterials of nobel nanoparticles/rare-earth. In addition, the structure and properties of obtained materials were investigated in detail.This paper consists of the following three chapters:1. The lanthanide-polyoxometalate (LnW10) complexes were bonded on the surface of silica nanoparticles modified by polyethyleneimine (PEI) with various sizes, which resulted in the formation of LnW10/PEI/SiO2(LnW10,Ln=Eu,Dy) particles. The hybrid core-shell particles were characterized by fourier transform infrared(FT-IR), scanning electronic microscope(SEM), luminescent spectra and transmission electronic microscope(TEM). The particles exhibited the fine spherical core-shell structure and the excellent luminescence properties. The luminescence spectra revealed that the fabrication of hybrid EuW10/PEI/SiO2particles with different sizes had an influence on the luminescent properties and the site symmetry of europium ions. The site symmetry of Eu3+was relatively higher and the intensity of its fluorescence was weaker with increase of the particle sizes.2. Stober silica particles were decorated with polyethyleneimine and silver nanoparticles and Eu-polyoxometalates were grafted on the surface of polyethyleneimine/silica spheres, and the bifunctional SiO2/EuW10/Ag nanoparticles with core-shell structure were obtained. The hybrid composite were characterated by FT-IR, Ultraviolet-visible spectroscopy(UV-vis), SEM, TEM, luminescent spectra and cyclic voltammetry (CV), respectively. The photoluminescence spectra showed that the incorporation of Ag nanoparticles changed the symmetrical environment of Eu3+and the energy could be more effectively transferred from ligand to lanthanide. The electrochemical activities of hybrid particles have been demonstrated by CV measurement. The catalytic results indicated that the hybrid materails showed the catalytic properties in the oxidation of styrene. The conversion of styrene is about52.1%and the selectivity of the benzaldehyde is about49.9%at1h.3. Stober silica microspheres with different particle size were prepared and PEI was employed as crosslink polymer to immobilize the Au nanoparticles and lanthanide-polyoxometalates on silica spheres, which resulted in the formation of bitifunctional composite microspheres of Silica/lanthanide-polyoxometalates/Au. The hybrid composite were characterated by FT-IR, UV-vis, SEM, TEM, luminescent spectra, powder X-ray diffraction and CV, respectively. The hybrid composite with core-shell structure were proved by SEM and TEM. The photoluminescence spectra showed that energy could be more effectively transferred from ligand to Eu3+with the incorporation of Au nanoparticles. Moreover, the symmetrical environment of Eu3+of the hybrid composite relatively lower with increase of the particle sizes. The composite particle was found to be catalytically active in the oxidation of hexene. The hybrid composite with smaller size showed the higher selectivity and the main product of the reaction is benzaldehyde and styrene oxide.