Controlled Growth of Ceria Nanoarrays on Anatase Titania Powder: A Bottom-up Physical Picture.

Abstract

The leading edge of catalysis research motivates physical understanding of the growth of nanoscale oxide structures on different supporting oxide materials that are themselves also nanostructured. This research opens up for consideration a diverse range of facets on the support material, versus the single facet typically involved in wide-area growth of thin films. Here, we study the growth of ceria nanoarchitectures on practical anatase titania powders as a showcase inspired by recent experiments. Density functional theory (DFT)-based methods are employed to characterize and rationalize the broad array of low energy nanostructures that emerge. Using a bottom-up approach, we are able to identify and characterize the underlying mechanisms for the facet-dependent growth of various ceria motifs on anatase titania based on formation energy. These motifs include 0D clusters, 1D chains, 2D plates, and 3D nanoparticles. The ceria growth mode and morphology are determined by the interplay of several factors including the role of the common cation valence, the interface template effect for different facets of the anatase support, enhanced ionic binding for more compact ceria motifs, and the local structural flexibility of oxygen ions in bridging the interface between anatase and ceria structures.