Synthesis And Characterization Of Luminescent Rare-earth Hybrid Nanomaterials

Hybrid nanomaterials have been novel functional materials widely utilized in thefields of optoelectronic, communication, biotechnology, medicine and bionics, owingto their unique properties. The rare earth luminescent hybrid nanomaterials withexcellent luminous performance, long fluorescence lifetime, play important roles inlighting, bio-imaging and bio-labeling. The research on synthesis and property of rareearth hybrid nanomaterials has attracted many researchers’ eyes. In this thesis, twodifferent hybrid nanomaterials are synthesized, of which luminescent light is in visibleand near infrared region respectively. Main research results are described as follows:1. We synthesized luminescence tuneable ceria-based CeO₂:Tb³⁺,Ce³⁺nanoparticles by a facile route, in which Ce³⁺was self-doped. This kind ofnanoparticles has a uniform morphology and a narrow size distribution with theaverage size of the particles around30nm. They are widely dispersed in aqueoussolution and stain stable luminescence, long lifetime, which are meaningful forbio-imaging and bio-labeling. According to TEM images and Nitrogenadsorption-desorption isotherms, small CeO₂:Tb³⁺nanocrystals are formed underhydrothermal condition, firstly; then, these nanocrystals assemble to nanoparticleswith average size around30nm. After ascorbic acid reduction, an amount of Ce⁴⁺inCeO₂:Tb³⁺nanoparticles convert to Ce³⁺. Excess Ce³⁺ions give rise to energy transferfrom Ce³⁺to Tb³⁺in CeO₂:Tb³⁺,Ce³⁺nanoparticles. These nanoparticles showintensity tuneable green luminescence, a long lifetime and low photobleaching inwater.2. Tuneable luminescent nanoparticles are synthesized by adding differentascorbic acid concentration. It is important in applications that synthesis ofnanoparticles can be controlled. Reactive oxygen species （ROS） can be scavenged bythese nanoparticles due to the high ratio of Ce³⁺/Ce⁴⁺in ceria. The luminescence intensity of CeO₂:Tb³⁺,Ce³⁺nanoparticles is sensitive to H₂O₂（a ROS） concentrations.With increased H2O₂concentration, the luminescence intensity of CeO₂:Tb³⁺,Ce³⁺nanoparticles is decreased gradually. The emission intensity can be recovered bytreating with ascorbic acid, and this cycling can be repeated, which reveals goodanti-fatigue properties of CeO₂:Tb³⁺,Ce³⁺nanoparticles. These attractive propertiesmake CeO₂:Tb³⁺,Ce³⁺nanoparticles potential materials for ROS detection.3. The near-infrared （NIR） luminescence graphene oxides/Er-8-hydroxyquinolinehybrid nanomaterial is prepared by a noncovalent approach. The rare-earth complexesthat are decorated on the graphene oxides planner with Ï€-Ï€ interactions have thespecific NIR luminescence. Luminescence in NIR region takes the advantages of hightransparency, reduced scattering and little influence of background caused by cellauto-fluorescence. The functional groups such as–OH,-COOH on the planner of thegraphene oxides increased the solubility and bio-compatibility of the hybrid material,which make it potential useful in bio-imaging and therapy.