Local environment of Fe dopants in nanoscale Fe : CeO2−x oxygen storage material. Issue 7 (23rd January 2015)

• Record Type: Journal Article
• Authors: Meledina, M.; Turner, S.; Galvita, V. V.; Poelman, H.; Marin, G. B.; Van Tendeloo, G.
• Is Part Of: Nanoscale. Volume 7:Issue 7(2015)
• Page Start: 3196
• Page End: 3204
• Publication Date: 2015-01-23
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c4nr06060a
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Nanoscale Fe : CeO2− x oxygen storage materials for chemical looping have been investigated at an atomic scale, before and after looping. Abstract : Nanoscale Fe : CeO2− x oxygen storage material for the process of chemical looping has been investigated by advanced transmission electron microscopy and electron energy-loss spectroscopy before and after a model looping procedure, consisting of redox cycles at heightened temperature. Separately, the activity of the nanomaterial has been tested in a toluene total oxidation reaction. The results show that the material consists of ceria nanoparticles, doped with single Fe atoms and small FeO x clusters. The iron ion is partially present as Fe 3+ in a solid solution within the ceria lattice. Furthermore, enrichment of reduced Fe 2+ species is observed in nanovoids present in the ceria nanoparticles, as well as at the ceria surface. After chemical looping, agglomeration occurs and reduced nanoclusters appear at ceria grain boundaries formed by sintering. These clusters originate from surface Fe 2+ aggregation, and from bulk Fe 3+, which "leaks out" in reduced state after cycling to a slightly more agglomerated form. The activity of Fe : CeO2 during the toluene total oxidation part of the chemical looping cycle is ensured by the dopant Fe in the Fe1− x Ce x O2 solid solution, and by surface Fe species. These measurements on a model Fe : CeO2− x oxygen storage material give a unique insight into the behavior of dopants within a nanosized ceria host, and allow to interpret a plethora of (doped) cerium oxide-based reactions.