Mesoporous CeO2 nanoparticles assembled by hollow nanostructures: formation mechanism and enhanced catalytic properties

Abstract

In this paper, novel hierarchically mesoporous CeO₂ nanoparticles assembled by hollow nanocones were prepared through a facile solvothermal strategy using Ce(HCOO)₃ as the precursor. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FE-SEM) and thermal gravimetric analysis (TGA) were utilized to characterize the products and research the formation mechanism. The whole synthesis process involves two steps: formation of Ce(HCOO)₃ nanoparticles constructed with nanocones at room temperature in an alkaline environment and oxidation induced phase transformation from Ce(HCOO)₃ to CeO₂ with formation of hollow nanocones assembled by nanocrystals in a solvothermal process at 150 °C. The as-prepared mesoporous CeO₂ nanoparticles with an average diameter of 500 nm displayed a high surface area of 147.6 m² g⁻¹ using N₂ adsorption and desorption measurement. The H₂-TPR test showed its great reduction behavior in a low temperature zone. By comparing the T100 temperature of CO conversion with a commercial sample (above 350 °C) and other reported samples (above 300 °C) in the literature, the mesoporous CeO₂ nanoparticles (270 °C) presented an excellent catalytic activity for CO oxidation.