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The almost monodisperse three dimensional (3D) porous CeO2 hollow nanospheres with a diameter of about 200–500 nm and rough surface have been synthesized by a facile template-free hydrothermal route. It was found that each hollow spherical nanostructure is composed of numerous nubbly nano-particles with several decade nanometers in diameter as the building blocks, which are randomly assembled with lower density to form a 3D porous structure. Many characterization means have been employed to study the CeO2 hollow nanospheres, including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman, and ultraviolet–visible spectrum. The 3D CeO2 hollow nanospheres own a cubic fluorite structure and many Ce3+ ions and oxygen vacancies exist in their surface. The morphology structure of samples, size of building blocks, and the oxygen vacancies may be the reason for the red-shifted in band gap of the 3D CeO2 hollow nanospheres. [ABSTRACT FROM AUTHOR]

The large-scale beautiful shuttle-like nanostructures with numerous nanorods assembling at both ends have been purposefully fabricated via a facile and efficient hydrothermal route. Various techniques have been applied to investigate the CeO nanostructures, including XRD, SEM, XPS, Raman spectra, PL spectra. The XRD results demonstrate that all the samples own a cubic fluorite structure of CeO with no other crystalline impurity phase. The results show that the morphology of the as-synthesized nanostructures gradually changes from rough shuttle-like structure to smooth shuttle-like structure with the increase of the amount of NHHCO. It is found that there are many Ce ions and oxygen vacancies in surface of samples, which can account for their similar room temperature photoluminescence emission peaks. Their PL intensity is different from each other, which may be attributed to the effect of different morphology and size of the samples. [ABSTRACT FROM AUTHOR]