Template-Free Synthesis and Self-Assembly of CeO₂ Nanospheres Fabricated with Foursquare Nanoflakes

Large-scale CeO₂ spherical architectures composed of numerous nanoflakes have been controllably prepared through a simple hydrothermal reaction without any template. The products were characterized with X-ray diffraction, nitrogen adsorption−desorption experiments, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the CeO₂ architecture ca. 100−230 nm in diameter was made up of many nanoflakes with a BET surface of 24 m²/g. The possible mechanism for the nanostructures formation was discussed. The catalytic performance of CeO₂ nanospheres and the direct-depositing CeO₂ nanoparticles in CO oxidation were also tested, and the catalytic results were compared and explained by analyzing the exposed planes of the two.