Facile Synthesis of Ceria Nanocrystals with Tuneable Size and Shape

Ceria (CeO2) possesses a distinctive redox property due to a reversible conversion to its nonstoichiometric oxide and has been considered as a promising catalyst in the oxidative coupling of methane. Since a heterogeneously catalytic process usually takes place only on the surface of catalysts, it is reasonably expected that the performance of a catalyst, such as CeO2, highly relies on its size- and shape-dependent surface structure. We report our recent progress in achieving exclusive crystal facet-terminated CeO2 nanocrystals using a shape-controlled synthesis protocol in a one-pot colloidal system. We modified a two-phase solvothermal approach to fabricate cubic and truncated octahedral CeO2 nanocrystals with a size-control. During the two-phase solvothermal process, we propose that the Ce-precursors transfer from the aqueous layer to the interface of the organic phase, promoted by the capping ligands (as known as phase-transfer catalysts), for the oxidation and nucleation, and subsequently form CeO2 nanocrystals in the organic layer. As different capping ligands favor binding on diverse crystal facets, tuning the composition of the capping ligand with a precise control could generate nanocrystals that are dominated by a single type of facets with a relatively narrow size distribution.