| Cerium oxide (CeO2) is an important rare earth oxide. Ceria with different morphology and doped cerium-based oxides have been widely applied in the field of catalysis, full cell, UV absorption and sensors due to its unique physical and chemical properties induced by the different crystal surface exposed, increased concentration of oxygen vacancies and enhanced oxygen storage/release capacity (OSC).In this paper, we adopt a hydrothermal precipitation method and synthesize Ce0.8M0.2O2 at 90℃for 24 h. The influence of the content of doped material and the precursor of cerium and base on the morphology and structure were investigated. The materials were characterized by XRD, SEM, Raman, XPS and H2-TPR and CO oxidation as a probe reaction to investigate catalytic properties of the relationship between structure and morphology. The synthesized Ce0.8M0.2O2 (M=La,Sm) nanorods maintain the cubic fluorite structure of CeO2 and show a large BET surface area (>70 m2/g). Meanwhile, the presence of Ce3+ lead to the more lattice defect for Ce0.8M0.2O2. Therefore , they show better catalytic performance on the CO oxidation reaction. Ce0.8La0.2O2 and Ce0.8Sm0.2O2 can reach a 100% conversion of CO at 300 and 350℃respectively.The morphology of Ce0.8M0.2O2 changed from nanorods to nanocubes through nanoparticles when controlled the reaction temperature and time. The combined results of XRD, Raman and H2-TPR show higher crystallinity of the cubic fluorite structure of the Ce0.8M0.2O2 with cubic morphology. While their surface area decreased from 84.7 to 8.9 m2/g. as well as the concentration of oxygen vacancies and lattice defeat. Ce0.8M0.2O2 with cubic morphology show decreased CO performance for the directed relation of catalytic performance to morphology and structure. Ce0.8La0.2O2 and Ce0.8Sm0.2O2 nanorods can reach a 100% conversion of CO at 300 and 350℃ respectively while in the case of nanocubic, the temperature was 500℃for CO reach complete oxidation. |
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