Figure 1.
a) Schematic representation of the regenerative capability and oxidation state switching of ceria NPs in an aqueous environment. The pictures of bottles containing the NP suspension in DI water indicate the color changes after different aging periods. The mechanism of oxidation-state change in the presence of hydrogen peroxide and hydroperoxyl radicals is shown (b) UV-Vis absorption spectra of ceria NP suspension indicate the shift in the absorption as a function of time. It is evident from the plots that the absorption spectra for freshly synthesized ceria NPs and those after 3 weeks of aging are almost identical.