Cerium Oxide Micro-nano-materials Hydrothermal Preparation And Performance Research

Ceria (CeO2) is an important light rare-earth product, which has a broad market applied prospect. Recently, the controls of morphology, size and applications of properties about CeO2 nanomaterials have been the key issues. In this dissertation, CeO2 micro and nano materials were synthesized by hydrothermal method. The effect factors and formation mechanisms were discussed. At the same time, the photocatalytic activity of CeO2 nanomaterials in the degradation of methylene blue (MB) under UV irradiation was also investigated. The main contents and results are discussed as follows:1. CeO2 nanospheres with diameter about 200 nm have been prepared by hydrothermal method using Ce(NO3)3-6H2O, chitosan and benzyl alcohol as raw materials at 200℃for 24 h. The powder X-ray diffraction pattern showed that the CeO2 nanospheres belong to the face centered cubic phase with calculated lattice parameters a=0.5411nm, b=0.5411nm and c=0.5411nm. Transmission electron microscopy micrographs studies reveal the as-prepared CeO2 nanospheres is composed of nanoparticles with crystalline size about 10 nm. BET (Brunauer, Emmett and Teller) studies showed that the CeO2 nanospheres had higher BET area of 108 m2/g and pore-size distributed at about 10 nm and 35 nm. Finally, the influences of the reaction conditions are discussed and a possible mechanism for the formation of CeO2 nanospheres is proposed.2. CeO2 microspheres with diameter about 5μm were synthesized by such conditions: Ce(NO3)3·6H2O and urea as reactants, citric acid as surfactant, the reaction temperature was 180℃and the reaction time was 20 h. When changed citric acid with CTAB, the products became CeO2 spindles. Finally, the influences of the reaction conditions are discussed and possible mechanisms for the CeO2 microspheres and spindles are proposed.3. The photocatalytic activity of CeO2 nanomaterials synthesized at different conditions under UV irradiation with methylene blue have been studied. It shows that the prepared CeO2 nanomaterials had higher catalytic activity than simple CeO2. The photocatalytic activity of CeO2 nanomaterial synthesized at 180℃for 24 h was the best, and the degradation rate is 94% in 6 h.