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

Abstract

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 °C and 25 °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 VO_x/CeO₂. Compared with traditional CeO₂ nanoparticles, the ceria nanosheets showed excellent catalytic oxidation activities.