Xiaofei Niu

Hydrothermal synthesis of 3D hierarchical porous CeO2 rugby-ball-like nanostructures with nanorods as building blocks

Rugby-ball-like CeO2 hierarchical porous structures have been successfully synthesized by a simple template-free hydrothermal method using CeCl3·7H2O as cerium, NH4HCO3 as precipitator and ethanediamine as surfactant. X-ray diffraction (XRD) inferred that the synthesized CeO2 microstructures exhibited a fluorite cubic structure. Moreover, the as-prepared CeO2 samples have a rugby-ball-like hierarchical porous structure assembled by numerous nanorods with a small diameter, and the oxygen vacancies and Ce3+ ions exist in the surface of samples. There is a red-shifting in the band gap of the material compared to bulk one, which is mainly attributed to the influences of the Ce3+ ions, oxygen vacancies and the morphology of the material.

Controlled synthesis and magnetic properties of thin CeO2 nanotubes by a facile template-free hydrothermal method

Uniform CeO2 nano-octahedrons and the straw-like CeO2 nanostructures assembled by numerous thin nanotubes have been successfully synthesized by a facile one-step hydrothermal synthesis route only using Ce(NO3)3·6H2O as cerium resource, Na3PO4·6H2O as mineralizer and no surfactant or template. The reaction time was systematically investigated. XRD, SEM, TEM, XPS, Raman scattering, Photoluminescence spectra and M-H curves were employed to characterize the samples. The results showed that both CeO2 nano-octahedrons and nanotubes owned a fluorite cubic structure and the octahedrons-like structures gradually transform into nanotubes with the increase of the reaction time. The possible formation mechanism based on nucleation-dissolution–recrystallization of nanoparticles was proposed. It is found that there are Ce3+ ions and oxygen vacancies in surface of samples. All the samples exhibited similar emission peaks of room temperature photoluminescence and the emission intensity increases with the increase of concentration of oxygen vacancies. The M-H curves of CeO2 nano-octahedrons and nanotubes exhibit excellent room-temperature ferromagnetism, which is likely attributed to the effects of the Ce3+ ions and oxygen vacancies.

Novel controlled hydrothermal synthesis of three different CeO2 nanostructures and their morphology-dependent optical and magnetic properties

In the work, we explored an efficient synthetic platform to purposefully fabricate CeO2 nanostructures with different morphologies of by controlling the different solution conditions. All the obtained samples were characterized by means of XRD, SEM, TEM, XPS, Raman scattering, UV–Vis, Photoluminescence (PL) spectra and M–H curves. The results show that all the samples have a cubic fluorite structure and the samples synthesized in alkaline, acidic and neutral aqueous solution display nanorod/nanotube, nano-plate and nano-octahedron structure, respectively. It was 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 Ce3+ ions, oxygen vacancies and the change of sample morphology. The existence and increase of Ce3+ ions and oxygen defects in the CeO2 samples can lead to a smaller band gap, stronger PL diffraction and elevated ferromagnetism.

Novel hydrothermal synthesis of hexagonal prism-like CeO2 nanotubes and their optical properties

Abstract The hexagonal prism-like CeO2 nanotubes have been successfully synthesized via a facile hydrothermal method using Ce(OH)CO3 hierarchical structures as precursors. X-ray diffraction inferred that the synthesized CeO2 nanotubes exhibited a fluorite cubic structure. The scanning electron microscope and transmission electron microscope revealed that the CeO2 samples have a hexagonal tube-like structure, while bundle-like hierarchical structure was obtained in original solution. X-ray photoelectron spectroscopy and the Raman spectroscopy reflected the existence of the oxygen vacancies and Ce3+ ions in the hexagonal CeO2 nanotubes. There is a red-shifting in the band gap of the material compared to bulk one, which is mainly attributed to the influences of the Ce3+ ions, oxygen vacancies and the novel morphology.