Synthesis of bundle-like CeO₂ nanofibers and their sub-microstructures

The simultaneous control of size, morphology, and size distribution of particles is a challenging topic for powder synthesis, and one-dimensional (1-D) nanostructures have attracted increasing attention due to their specific properties. In the present study, 1-D CeO₂ was synthesized via a solvothermal treatment using Ce(NO₃)₃·6H ₂O and CO(NH₂)₂ in ethanol without the use of any template or surfactant. A SEM study revealed 1-D CeO₂ fibers with perfect profile, well-dispersed state, and more uniform size distribution. The diameter of the fibers was about 50nm and the length was 200-800 nm. An in-depth TEM observation revealed that a 1-D profile was formed by agglomeration of large numbers of nanoparticles during an early stage of the reaction. Then, the nanoparticles were gradually fused together to form a 1-D fiber with a smooth surface and a sub-microstructure, namely, the CeO₂ fibers were assembled from many sub-nanofibers. Finally, some possible evolution mechanisms for the formation of bundlelike CeO₂ nanofibers were discussed.