Facile Low-Temperature Synthesis of Ceria and Samarium-Doped Ceria Nanoparticles and Catalytic Allylic Oxidation of Cyclohexene

CeO2 as one of the most promising oxidation catalysts has attracted much attention because of its superior performance. The extent of oxidation properties is controlled by the ration of Ce3+/Ce4+, particle size, and surface area. Here, a facile low-temperature aqueous solution-based chemical route for the synthesis of CeO2 and samarium-doped CeO2 (Sm-CeO2) nanoparticle aggregates, with high content of Ce3+ and surface area, using aqueous solution of ammonium carbonate complex of cerium is presented. The morphologies and structures of the prepared CeO2 nanoparticle were characterized by X-ray diffraction (XRD), thermal analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen-temperature programmed desorption. The synthesized CeO2 and Sm-CeO2 nanoparticle aggregate showed significantly improved catalytic activity toward allylic oxidation to corresponding en-ones compared to bulk CeO2. The present method provides a new and facile strategy toward the synthesis of CeO2 and Sm-CeO2 nanoparticle aggregates with extensive applications.