Nanostructured ceria-based catalysts for soot combustion: investigations on the surface sensitivity

tA set of ceria nanomaterials with different topological and textural properties has been prepared toinvestigate the shape-dependency activity of ceria towards soot combustion under different reactionconditions (namely in “loose” and “tight” contact). The physico-chemical properties of the prepared cat-alysts have been studied using complementary techniques. The best performances, in terms of the totaloxidation of soot, have been achieved for the CeO2-nanocubes, due to the abundance of coordinativeunsaturated atomic sites on the (1 0 0) and (1 1 0) exposed surfaces (namely truncated nanocubes). How-ever, better results, in terms of the onset of soot oxidation, have been obtained for high-surface-areamaterials, thus reflecting the key role of surface area at low temperatures. Activity tests have suggestedthe surface-sensitivity of soot oxidation over the prepared ceria-based materials, when the reaction tem-perature was above 410◦C or 370◦C (in “loose” or “tight” conditions, respectively). On the other hand, thereaction has appeared surface-insensitive at a lower temperature. Hence, soot oxidation over these ceriacompounds can be considered a reaction that displays both surface-sensitive and surface-insensitivebehaviour, which depend on the experimental conditions