Tuning the shape of ceria nanomaterials for catalytic applications

The design and fabrication of catalytic materials is a key issue in heterogeneous catalysis to achieve desired performance. Traditionally, the main theme is to reduce the size of the catalyst particles as small as possible for increasing the number of active sites. In recent years, the rapid advancement in materials science has enabled us to fabricate catalyst particles with tunable shape at nanometer level. Through morphology control of nanoparticles by exposing highly reactive crystal planes, their catalytic properties can be drastically enhanced. Therefore, both size modulation and shape control of catalyst nanoparticles can be achieved independently or synergistically to optimize their catalytic behavior. We highlight, in this review, the recent progress in shape control of CeO₂ materials that are widely used as crucial components or structural and electronic promoters in heterogeneous catalysts. We first summarize the major synthetic strategies and characteristics of shape-controlled CeO₂ nanomaterials. We then survey morphology-dependent nanocatalysis of CeO₂ and Au-CeO₂ catalysts. We understand now that the enhanced catalytic property of the Au-CeO₂ system is closely related to the unique interaction between the gold nanoparticles and the ceria support; such an interaction originates from the particular shape of ceria, especially the exposed facets. Finally, we present our understanding of the morphology-dependent nanocatalysis and provide our perspectives on their future potential and development. The fundamental understanding of the nature of the intrinsic active sites of the shape-tunable ceria nanostructures, enclosed by reactive crystal planes/facets with unique properties, is expected to provide highly efficient nanocatalysts for practical applications.