The effect of AuNP modification on the antioxidant activity of CeO2 nanomaterials with different morphologies

Abstract AuNP-modified CeO 2 nanomaterials with three different morphologies were prepared and their antioxidant abilities were evaluated by the UV method; then, the mechanism of the effect of AuNPs was further explored. It was found that AuNPs’ effect on the antioxidant properties of CeO 2 varied with different morphologies and sample concentrations. At lower concentrations, AuNPs improved the antioxidant abilities of CeO 2 nanorods and nanoparticles and reduced that of CeO 2 nanocubes. However, at higher concentrations, the antioxidant activities of Au/CeO 2 nanorods and nanoparticles were decreased and that of Au/CeO 2 nanocubes was enhanced. It was observed that AuNPs promoted the generation of Ce 3+ on the surfaces of CeO 2 nanorods and nanoparticles, causing increased antioxidant activity, while they inhibited the generation of Ce 3+ on nanocubes, accompanied with decreased activity. In addition, at higher concentrations, more exposed active sites on the surfaces of Au/CeO 2 nanorods and nanoparticles were hidden due to severe aggregation, resulting in decreased antioxidant activity compared to CeO 2 ; less aggregation was found for Au/CeO 2 nanocubes, and their antioxidant activity was better than that of CeO 2 . Furthermore, the behaviour of nanocubes was found to be opposite to that of nanorods and nanoparticles, possibly attributed to the particularity of (1 0 0) crystal planes, which may change the way that electrons transfer at the interface.