Tuning, via Counter Anions, the Morphology and Catalytic Activity of CeO2 Prepared under Mild Conditions

Counter anion induced morphologies of CeO2 synthesized under non-hydrothermal conditions show different soot oxidation activities. [Display omitted] ► Counter anion induced CeO2 nanorod and nanoflower morphologies were synthesized. ► The samples exhibit morphology dependent physicochemical and optical properties. ► Surface morphologies of CeO2 influence the redox property, OSC and surface acidity. ► Soot oxidation is rapid on CeO2 nanorods as compared to CeO2 nanoflowers. Advanced synthetic methods under mild and controlled conditions for the synthesis of nanocrystals with specific shapes and exposed surfaces are very important for understanding the surface related properties and to explore their structure–property relationship for various potential applications. Here, we report the synthesis of highly uniform CeO2 nanorods and nanoflowers in large scale using non-hydrothermal homogeneous precipitation method with urea as a precipitating agent and CTAB as a shape directing agent. Uniform microstructures of CeO2 samples were selectively synthesized using chloride and nitrate as the counter anions. The samples were characterized by thermal analysis, X-ray diffraction, N2 adsorption–desorption isotherms, SEM, TEM, UV–Vis-DRS, and Raman spectroscopy, and temperature programmed reduction as well as desorption methods. The results show that the physicochemical and optical properties of CeO2 samples significantly differ with their surface microstructure and morphology. They also strongly influence the redox property, oxygen storage capacity, and surface acidity of the CeO2 samples. The CeO2 samples with different morphologies were tested for their soot oxidation activity. The CeO2 sample with nanorod morphology was found to be more active due to larger CeO2/soot interface than the CeO2 sample with nanoflower morphology.