Sustainable and Facile Route to Nearly Monodisperse Spherical Aggregates of CeO2 Nanocrystals with Ionic Liquids and Their Catalytic Activities for CO Oxidation

Abstract

This article reports a novel preparation of nearly monodisperse spherical aggregates of CeO2 nanocrystals by using ionic liquid (1-hexadecyl-3-methylimidazolium bromide, C16MimBr) as both template and solvent. The products were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV−vis spectroscopy, FT-IR spectroscopy, and N2 adsorption−desorption methods. The spherical aggregates, with average diameter of 100 − 150 nm, are composed of ca. 3.5 nm CeO2 nanocrystals as building units, giving rise to three-dimensional (3D) open porous structures with high Brunauer−Emmett−Teller surface area of 119 m2·g−1. Mesoporous CeO2 with surface area up to 227 m2·g−1 was prepared by simply tuning the amount of the ionic liquids. Loaded with 5 wt% CuO, both the spherical aggregates and the mesoporous CeO2 exhibit high catalytic activities for CO conversion with 100% ...