Facile synthesis of single-crystalline CeO₂ nanorods from aqueous CeCl₃ solutions

Fluorite-type CeO₂ nanorods were synthesized from aqueous CeCl₃ solutions containing polyethylene glycol, NaOH, and NaCl. The solutions were hydrothermally treated at 140°C, resulting in the formation of nanorod-like precipitates. Further annealing of the precipitates led to the growth into well-defined nanorods 5-10 nm in diameter and 50-200 nm in length. It was found that the addition of NaCl to the solution could enhance the one-dimensional growth of CeO₂ and reduce the degree of aggregation. A high-resolution transmission electron microscopic observation revealed that the nanorod was single-crystalline and its growth direction was along the [110] axis of the cubic CeO₂ structure. Our results then demonstrated that the unusually [110]-oriented CeO₂ nanorods could be grown by a facile synthesis method.