Antioxidant activity of cerium oxide as a function of europium doped content

Doping metallic oxides with trivalent ions can enhance functional properties as antioxidant activity because of the increment of oxygen vacancies. In this work, Sol-gel derived cerium oxide particles, were doped with europium (0, 2.5, 5, 7.5, 10, 12.5, 15 and 20 mol%) with the aim to analyze the effect of Eu content on antioxidant activity. Heat-treated at 400 °C, doped ceria was evaluated by an in vitro ABTS• radical scavenging assay, where the inhibition of CeO₂:Eu³⁺ doped at 5 mol% was 1.3 times higher than the commercial antioxidant. A special absorption of OH groups related to oxygen vacancies was observed by FTIR. The typical-FCC structure was detected for all samples, using XRD. SEM analyses show porous and spongy agglomerated particles with an average size of 230 nm, measured by DLS. The structural and morphological results are quite similar for all Eu³⁺ contents, therefore, the observed free radical scavenging capacity is strongly dependent of the chemical composition.