Concentration of Ce³⁺ and Oxygen Vacancies in Cerium Oxide Nanoparticles

Abstract

Temperature variations of the electron magnetic resonance (EMR) spectra and magnetization measurements are used to show that Ce3+ ions in concentration ≃18% are present in 3 nm CeO2 nanoparticles supported on silica aerogel. It is argued that the presence of Ce3+ implies the defect structure CeO2- x for ceria nanoparticles due to oxygen vacancies. This transformation of Ce4+ to Ce3+ driven by oxygen vacancies may be the key to understanding the catalytic properties of ceria.

Cerium oxide nanoparticle: a remarkably versatile rare earth nanomaterial for biological applications

“…However, its structural properties allow CeONP to be restored to its initial state. 32 The kinetics measured by Seal et al 43 showed excellent activity for CeONP (3-5 nm), with a constant catalytic rate that exceeded the one determined for the enzyme SOD.…”

“…31 In general, the fraction of Ce 3 þ ions in the particles increases with decreasing particle size. The techniques used to determine the Ce 3 þ /Ce 4 þ ratios include X-ray photoelectron spectroscopy, 31 X-ray absorption nearedge spectroscopy, 32 electron magnetic resonance spectroscopy 33 and UV-visible absorption spectroscopy. 34 It is remarkable and interesting that CeONP could have a dual role as an oxidation catalyst and reduction catalyst, depending on the reaction conditions.…”

“…However, its antioxidative quality is only effective when the two enzyme-like activities of CeONP are coordinated, that is, the H 2 O 2 decomposition rate should be equal to or greater than its generation rate. According to recent reports, many factors such as particle size, Ce 3 þ /Ce 4 þ ratio, 32,43,50 buffer species 51 and pH conditions 51,52 could affect the enzyme-mimetic properties of CeONP.…”

Synthesis and characterization of nanometric strontium-doped ceria solid solutions via glycine-nitrate procedure

“…Starting chemicals used for the synthesis of powders were strontium nitrate Sr(NO 3 ) 3 , cerium nitrate hexahydrate [Ce(NO 3 ) 3 ·6H 2 O] and glycine (NH 2 CH 2 COOH) from Wako Chemical Industries, Ltd., Japan. The compositions of the starting reacting mixtures were calculated according to the nominal composition of the final reaction product.…”

Cerium oxide-chitosan based nanobiocomposite for food borne mycotoxin detection

“…1͑a͔͒ of the CeO 2 , synthesized using coprecipitation method exhibits characteristic diffraction planes corresponding to CeO 2 fluorite structure. 2,15 However, the observed reflection planes are broad due to small particle size ͑ϳ10 nm͒ estimated using Scherrer's formula. The incorporation of NanoCeO 2 in CH matrix has been confirmed using SEM wherein, regular planner morphology of CH ͑Ref.…”