Controllable preparation of CeO2 nanostructure materials and their catalytic activity

Well-crystalline CeO2 nanostructures with the morphology of nanorods and nanocubes were synthesized by a template-free hydrothermal method. X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption measurements were employed to characterize the synthesized materials. The reducibility and catalytic activity of nanostructured CeO2 were examined by hydrogen temperature-programmed reduction (H2-TPR) and CO oxidation. The results showed that CeO2 nanorods could be converted into CeO2 nanocubes with the increasing of the reaction time and the hydrothermal temperature, CeO2 nanorods became longer gradually with the increasing of the concentrations of NaOH. H2-TPR characterization demonstrated that the intense low-temperature reduction peak in the CeO2 nanorods indicated the amount of hydrogen consumed is larger than CeO2 nanocubes. Meantime the CeO2 nanorods enhanced catalytic activity for CO oxidation, the total conversion temperature was 340°C. The reasons were that CeO2 nanorods have much smaller crystalline sizes and higher surface areas than CeO2 nanocubes.