Great Influence of Anions for Controllable Synthesis of CeO2 Nanostructures: From Nanorods to Nanocubes

Controllable synthesis of well-shaped nanocrystals is of significant importance for understanding the surface-related properties as well as for the exploration of potential applications. Herein, CeO2 nanorods and nanocubes were selectively synthesized using cerium(III) chloride and cerium(III) nitrate as precursor, respectively. Counter anions of the cerium source were crucial to the shapes of the resulting products. Intriguingly, the as-synthesized nanorods could be converted into nanocubes by the addition of an appropriate amount of NO3- ions into the hydrothermal reaction. The NO3- ions are considered as both a capping agent and an oxidizer during the formation of CeO2 nanocubes. Moreover, the influences of several others anions are investigated. Br-, I-, and SO42- ions have similar roles to Cl- ions, which lead to the formation of nanorods. The introduction of BrO3- ions can bring on the generation of irregular nanoparticles because they can function as an oxidizer but not a capping agent. The anion-induced controllable growth process is simple and low cost, which makes this strategy potentially useful for the preparation of other faceted nanostructures.