Characterization of cerium dioxide nanoparticles prepared by supercritical water oxidation

Abstract

CeO 2 nanoparticles with high purity and crystallinity were prepared by a continuous supercritical water oxidation (SCWO) reaction. The phase composition, microstructure, and morphology of the prepared CeO 2 particles were characterized by X-Ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), BET specific surface area (BET), and X-ray photoelectron spectroscopy (XPS). The size distribution of the particles is narrow with an average particle size between 10 and 13 nm; the diameter decreased gradually as the Ce(NO 3 ) 3 Á 6H 2 O concentration in the preparation increased. The BET results show an increase in the products' specific surface area as the Ce(NO 3 ) 3 Á 6H 2 O concentration increased, with an average surface area of 48 m 2 g À 1 . SEM micrographs reveal that the CeO 2 particles are spherical, and that higher Ce(NO 3 ) 3 Á 6H 2 O concentrations are conducive to the formation of smaller particles. However, excess Ce(NO 3 ) 3 Á 6H 2 O caused serious agglomeration, due to the higher surface energy. XPS patterns indicate that Ce(III) was almost completely oxidized to Ce(IV) in the reaction, and that the binding capacity of Ce-O reduced gradually with increasing concentrations of Ce(NO 3 ) 3 .

Continuous Hydrothermal Synthesis of Inorganic Nanoparticles: Applications and Future Directions

“…(15) Develop cleaner particles for biomedical use that can meet regulatory hurdles. 522 (16) Developments in catalysis to explore the effects of NP size (e.g., rounded particles rather than faceted 663 ) or shape (such as faceted Cr-doped ceria) 664 or doped activating metals 665 that can improve the stability and performance of catalysts (e.g., lowering operational temperature).…”