Structural and physical-chemical characterization of redox active CeO2 nanoparticles synthesized by precipitation in water-alcohol solutions.

A set of cerium dioxide nanoparticles (CeO₂ NPs) was synthesized by precipitation in water-alcohol solutions under conditions when the physical-chemical parameters of synthesized NPs were controlled by changing the ratio of the reaction components. The size of CeO₂ NPs is controlled largely by the dielectric constant of the reaction solution. An increase of the percentage of Ce³⁺ ions at the surface was observed with a concomitant reduction of the NP sizes. All synthesized CeO₂ NPs possess relatively high positive values of zeta-potential (ζ > 40 mV) suggesting good stability in aqueous suspensions. Analysis of the valence- and size-dependent rate of hydrogen peroxide decomposition revealed that catalase/peroxidase-like activity of CeO₂ NPs is higher at a low percentage of Ce³⁺ at the NP surface. In contrast, smaller CeO₂ NPs with a higher percentage of Ce³⁺ at the NP surface display a higher oxidase-like activity. [ABSTRACT FROM AUTHOR]