Enhancement of antioxidant activity of well dispersed core-shell structured CeO2 coating Au nanorods under visible light irradiation.

Gold nanoparticle (AuNP) modification shows great advantages in improving the antioxidant activity of nanoCeO(2). However, the improved effect of AuNP modification becomes smaller and even results in the decrease of antioxidant ability due to severe aggregation with increasing nanomaterial concentration. Additionally, the effects of photo-properties of AuNPs on the antioxidant activity of nanoCeO(2) have not been studied. In response to these problems, core-shell-shaped Au@CeO2 was synthesized which took Au nanorods (AuNRs) as carriers and had a layer of CeO2 NP coating. The antioxidant activity of Au@CeO2 was evaluated by the UV-vis method in the methyl violet-Fenton system. Results showed that AuNRs could improve the antioxidant activity of nanoCeO(2) due to the increase in the amount of Ce3+ on the surface of nanoCeO(2), and the enhancing effect remained across the whole experimental concentration range due to the good dispersibility of AuNRs. Additionally, a further increase in the antioxidant ability of Au@CeO2 was found with 5 min visible light irradiation, and continuous irradiation during a 25 min time reaction, which resulted in more obvious enhanced antioxidant ability. This phenomenon was attributed to the localized surface plasmon resonance of AuNRs triggered by photons which induced charge transfer from AuNRs to nanoCeO(2), thus making the cyclic transformation between Ce3+ and Ce4+ easier.