Template-Free Hydrothermal Synthesis, Mechanism, and Photocatalytic Properties of Core–Shell CeO2 Nanospheres

CeO 2 nanospheres with the core–shell nanostructure have been successfully synthesized by a template-free hydrothermal method. The structures, morphologies and optical properties of core–shell CeO 2 nanospheres were analyzed by X-ray diffraction (XRD), TG, Fourier transform infrared spectroscopy, XRD, EDS, SAED, scanning electron microscopy and transmission electron microscopy, UV–Vis diffuse reflectance spectra, Raman analyses. The degradation efficiencies of core–shell CeO 2 nanospheres for methyl orange were as high as 93.49, 95.67 and 98.28% within 160 min, and the rates of photo degradation of methyl orange by core–shell CeO 2 nanospheres under UV-light were 0.01693, 0.01782 and 0.02375 min −1 . Methyl orange was degraded in photocatalytic oxidation processes, which mainly gave the credit to a large number of reactive species including h + , surface superoxide species ·O 2 − , and ·OH radicals. The core–shell structure, small crystallite size and the conversion between Ce 3+ and Ce 4+ of CeO 2 nanospheres were of importance for its catalytic activity. These results demonstrated the possibility of improving the efficient catalysts of the earth abundant CeO 2 catalysts.