The Synthesis And Performance Study Of CeO₂Based Nanomaterials

Rare earth compound material has became very popular for itsunique4f layer electronic structure, widely used in many fields such ascatalytic fields, solid fuel cells fields, gas sensors, ceramics fields and soon. Our country has rich rare earth resources, rare earth resourcesdevelopment and utilization have an inestimable role and special strategicposition in today's economic development.CeO₂is an important rare earth compound, it has a far-rangingapplications in catalysis and the crucial application as promoters ofthree-way catalysts due to their reversible redox and oxygen storageability arising from the facile cycling between Ce³⁺and Ce⁴⁺. Comparedto the single nano structure, nano composites provide a new road to getsuperior performance of materials by consisting the advantages ofmaterials with different composition and properties into the same system.Nano composites is becoming a hot spot in the study of nanometermaterials synthesis. Based on the above two points, the focus of thispaper is CeO₂based nanomaterials. The performance of CeO₂basednanomaterials is controlled by the doped elements, size and morphology structure, further more, size and morphology structure is directlyrelationed with the synthesis method. The fabrication of various CeO₂based nanomaterials with well-controlled morphology, phase purity,chemical composition and desirable properties are has importantscientific and social value.Herein, we report on a general colloid synthesis for CeO₂-Al₂O₃,CeO₂-SiO₂and CeO₂-TiO₂composites nanospheres which use alcohol asthe solvent and without other surface active agent. Nano spherical particlehas a uniform size distribution, core-shell structure and high specificsurface. We study the Kirkendall diffusion process from the perspectiveof kinetic and thermodynamics and show how thermdynamics and kineticfactors govern the diffusion process and the evolution of CeO₂basedoxides. In CeO₂-Al₂O₃system, it is shown that the morphologies ofCeO₂-Al₂O₃nanostructures could be adjusted by Ce/Al molar ratio andthe temperature. CeO₂-Al₂O₃system provide a sound experimentaldemonstration to show the diffusion process is not govern by a singledriving force, but a synergism of thermdynamic and dynamics. InCeO₂-SiO₂system, the CO oxidation reaction result show that thecatalytic performance is influenced by the morphology structure. WhenCe/Si=1:0.3(molar ratio), CeO₂-SiO₂has the best CO catalytic activityfor its hollow structure and high specific surface and much pore sizedistribution. In recent years, photocatalysis technology has a far-rangingapplication in water treatment. Nano TiO₂and CeO₂is commonphotocatalysts. In this paper, near monodisperse nanoparticles andnanorods TiO₂have been synthesized by hydrothermal method. Theeffects of surface modification, morphology, Ce doped quantity inphotocatalytic reaction are investigated. Experiment results show that thesurface modification can improve photocatalysis activity, thephotocatalytic activity of nanorods TiO₂doped with Ce is higher than thatof nanoparticles, there exists an optimal Ce doped quantity.