Template-free and non-hydrothermal synthesis of CeO2 nanosheets via a facile aqueous-phase precipitation route with catalytic oxidation properties

Two types of CeO2 nanosheet, petal-like and belt-like, were synthesized using a facile aqueous phase precipitation method with NH4HCO3 as the precipitant at 0 degrees C and 25 degrees C, without hydrothermal or solvothermal treatment, without template or surfactant and without organic solvent. The reaction temperature and the supersaturation played key roles in the formation of the ceria nanosheets, namely, a lower temperature and higher supersaturation were favorable for the synthesis of sheet-like CeO2 by the oriented aggregation of the as-synthesized nanocrystalline precursors, whereas elevated temperatures could cause the dissolution-recrystallization of the precursors and promote the Ostwald ripening process, and finally polyhedral CeO2 could be obtained via thermal decomposition of the precursors. The catalytic oxidation properties were investigated using the catalytic oxidation of CO over CeO2 and the catalytic combustion of 1,2-dichloroethane over VOx/CeO2. Compared with traditional CeO2 nanoparticles, the ceria nanosheets showed excellent catalytic oxidation activities.