Activation of Oxygen in Ce2Zr2O7+x across Pyrochlore to Fluorite Structural Transformation: First-Principles Analysis

Gupta, Asha and Kumar, Anil and Waghmare, U V and Hegde, M S (2017) Activation of Oxygen in Ce2Zr2O7+x across Pyrochlore to Fluorite Structural Transformation: First-Principles Analysis. In: JOURNAL OF PHYSICAL CHEMISTRY C, 121 (3). pp. 1803-1808.

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Abstract

Cationic substitution of zirconium in ceria (CeO2) greatly improves its oxygen storage capacity (OSC) and thermal stability. Although the fluorite structure of Ce0.5Zr0.5O2 (Ce2Zr2O8) exhibits good oxygen storage and release properties, its reduced counterpart Ce2Zr2O7 in the pyrochlore structure derived from the fluorite structure does, not. Here, we present an analysis of the structural evolution of Ce2Zr2O7+z from pyrochlore-Ce2Zr2O7 (z = 0) to fluorite-Ce2Zr2O8 (z = 1) using first-principles density functional theoretical calculations and bond-valence theory and correlate the consequent activation of oxygen to the observed oxygen storage capacity. The gradual addition of oxygen atoms to the otherwise ordered vacant tetrahedral sites for anions in pyrochlore-Ce2Zr2O7 structure will lead to a transition to fluorite-Ce2Zr2O8 structure, and we demonstrate,that this transition involves an increase in the number of weakly bonded, activated oxygen sites that areliertinent to higher OSC observed for the fluorite-Ce0.5Zr0.5O2 structure. The structural descriptors of OSC demonstrated:here will facilitate the understanding and rational design of oxide materials with improved OSC, which is key to catalyzing a number of reactions for Various applications.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY C
Publisher:	AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	21 Mar 2017 09:40
Last Modified:	21 Mar 2017 09:40
URI:	http://eprints.iisc.ac.in/id/eprint/56410

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