Fabrication of three dimensional CeO2 hierarchical structures: Precursor template synthesis, formation mechanism and properties

In this paper, three dimensional mesoporous CeO2 hierarchical structures were synthesized through the thermal decomposition of cerium formate precursors, which were prepared by a solvothermal method. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), and Thermal gravimetric (TG) was applied to characterize the precursors. Urchin-like Ce(HCOO)(3) precursors were prepared using dimethyl sulfoxide (DMSO) and ammonia solution (1 M) as solvent and base source, respectively, while coral-like Ce(HCOO)(3) precursors were prepared using dimethyl formamide (DMF) and NH4HCO3 as solvent and base source, respectively. The formation mechanism of the hierarchical structured precursors was proposed involving a process of anisotropic growth-H2O induced self-assembly-oriented aggregation and disassembly-Ostwald ripening. CeO2 hierarchical structures were obtained by annealing the corresponding Ce(HCOO)(3) precursors at 400 degrees C for 60 min. N-2 adsorption-desorption isotherms indicate that both CeO2 hierarchical structures derived from their Ce(HCOO)(3) precursors display large surface areas and high pore volumes. In addition, the as-prepared CeO2 catalysts with hierarchical structures are highly active for conversion of CO to CO2.