Aqueous Route to Size-Controlled and Doped Organophilic Ceria Nanocrystals

This paper presents an aqueous route to size-controlled and doped CeO 2 nanoparticles using the Ce-oleate complex as a chemically modified precursor. In this synthesis, a hydrolytic condensation of Ce-oleate complex by aqueous ammonia solution at room temperature leads to 2.2 nm sized CeO 2 nanocrystals. These products are dispersible in nonpolar solvents owing to the hydrophobic nature of the surface oleate ligand. Moreover, the size of the nanocrystals is controllable up to 5.2 nm by subsequent hydrothermal treatment at 200 °C. The proposed method can be extended for the synthesis of rare earth-doped CeO 2 nanocrystals as well. The Gd 3+ doped CeO 2 nanocrystals synthesized by the proposed method exhibit a spherical shape (size ∼ 3.2 nm) and have a designed chemical composition by energy dispersive X-ray analysis, X-ray diffraction, Raman scattering, and transmission electron microscopy.