Morphological Phase Diagram of Biocatalytically Active Ceria Nanostructures as a Function of Processing Variables and...

We rationalize how fluorite-structured CeO₂ , which is crystallographically isotropic, can grow anisotropically (without templates) to form nanoparticles, rods, and cubes. In particular, single-crystalline and monodispersed cubic CeO₂ nanoparticles, nanorods, and nanocubes have been selectively synthesized by a very simple, efficient, and economical hydrothermal process using different NaOH concentrations, and Ce(NO₃ )₃ as the cerium precursor. High-resolution transmission electron microscopy reveals nanomaterials with differently exposed crystal planes: {111} and {100} for nanoparticles, {110} and {100} for nanorods, and {100} for nanocubes. During the preparation of the CeO₂ nanomaterials, the formation of intermediate anisotropic Ce(OH)₃ species under basic conditions and their conversion into CeO₂ at higher temperature are key factors responsible for the shape evolution. Atomistic computer simulations were used to help rationalize how the synthetic conditions impact upon the morphology of the nanomaterial. The synthesized CeO₂ nanoparticles and nanorods demonstrate higher catalase mimetic activities than the nanocubes.