Simple and efficient controlled hydrothermal synthesis of elliptic-triangle-like CeO2 nanosheets: precursor synthesis, tuneable morphology and optical properties

The elliptic-triangle-like CeO2 nanosheets with many fissures have been purposefully fabricated via controlling the morphology of CeCO3OH precursors by an efficient hydrothermal route. The X-ray diffraction results indicate that the calcined samples have a cubic fluorite structure of CeO2 with no crystalline impurity phase. The scanning electron microscope images display that the morphology of the as-synthesized nanostructures gradually changes from diamond-like to tabular, then to elliptic-triangle-like nanosheet, and finally to fireworks-like/circular nanosheets mixed structure with the decrease of reaction temperature. X-ray photoelectron spectroscopy and Raman analyses demonstrate that there are Ce3+ ions and oxygen vacancies in the surface of samples. It is also found that there is a red-shifting in the band gap of the obtained material compared to bulk one, which is mainly attributed to the influences of the Ce3+ ions, oxygen vacancies and the morphology. All the samples exhibit the similar emission peaks of room temperature photoluminescence and the emission intensity increases with the increase of concentration of oxygen vacancies.