Low pressure induced porous nanorods of ceria with high reducibility and large oxygen storage capacity: synthesis and catalytic applications

Abstract

Ceria (CeO₂) is finding prolific industrial applications due to its unique redox properties. Such properties, dominated by structural defects that are primarily oxygen vacancies associated with the Ce³⁺/Ce⁴⁺ redox couple, can be modulated and optimized by controlling the size and morphology of the material, in particular those that are nanostructured (nanoceria). We report herein a new form of nanoceria prepared by a two-step hydrothermal synthesis. In the first-step hydrothermal treatment, the low reaction pressure is critical for the formation of a Ce(OH)₃/CeO₂ precursor. A subsequent hydrothermal step of dehydration and oxidation of the precursor nanorods led to the production of porous nanorods of ceria. The porous nanorods of ceria have been found to display enhanced reducibility and capacity for oxygen storage (900.2 μmol O₂ per g) as a result of their significantly increased surface area and defects over other forms of nanoceria, including nanoparticles, non-porous nanorods, nanocubes, and nanooctahedra. Their much improved activities have also been demonstrated in a benchmark reaction – catalytic oxidation of CO. The high catalytic activity of porous nanorods of ceria indicates their potential as the catalysts or supports or promoters for advanced oxidative processes for waste treatment and environmental remediation.