A surfactant and template-free route for synthesizing ceria nanocrystals with tunable morphologies

Nanosized crystalline ceria (CeO₂) is synthesized through a surfactant- and template-free solution precipitation-hydrothermal method. We report that pure CeO₂ nanocrystals with shapes consisting of nanospheres, nanowires, and nanorods can be obtained simply by varying the anionic composition or the type of counter ion, such as chloride, nitrate and phosphate in solution before the hydrothermal treatment. The shape-controlling effect of these anions is explained by the selective interaction of these ions with specific facets of CeO₂, leading to the growth of CeO ₂ nanocrystals with varying morphologies. Unlike techniques that require the use of organic and inorganic additives or templates, the new methodology represents a simple yet effective means to fabricate CeO₂ nanowires or nanoparticles with the potential to be further tuned to provide a morphologically controllable route for tailoring and designing CeO₂ nanomaterials for a wide variety of applications.