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Low valence cation doping of bulk Cr2O3: Charge compensation and oxygen vacancy formation
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Accepted Version
Date
2016-09
Authors
Carey, John J.
Legesse, Merid
Nolan, Michael
Journal Title
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Publisher
American Chemical Society
Published Version
Abstract
The different oxidation states of chromium allow its bulk oxide form to be reducible, facilitating the oxygen vacancy formation process, which is a key property in applications such as catalysis. Similar to other useful oxides such as TiO2, and CeO2, the effect of substitutional metal dopants in bulk Cr2O3 and its effect on the electronic structure and oxygen vacancy formation are of interest, particularly in enhancing the latter. In this paper, density functional theory (DFT) calculations with a Hubbard + U correction (DFT+U) applied to the Cr 3d and O 2p states, are carried out on pure and metal-doped bulk Cr2O3 to examine the effect of doping on the electronic and geometric structure. The role of dopants in enhancing the reducibility of Cr2O3 is examined to promote oxygen vacancy formation. The dopants are Mg, Cu, Ni, and Zn, which have a formal +2 oxidation state in their bulk oxides. Given this difference in host and, dopant oxidation states, we show that to predict the correct ground state two metal dopants charge compensated with an oxygen vacancy are required. The second oxygen atom removed is termed "the active" oxygen vacancy and it is the energy required to remove this atom that is related to the reduction process. In all cases, we find that substitutional doping improves the oxygen vacancy formation of bulk Cr2O3 by lowering the energy cost.
Description
Keywords
Generalized gradient , Approximation , Density-functional theory , Total-energy calculations , Wave basis set , Electrical-conductivity , Electronic-structure , Magnetic-properties , Self-diffusion , Ab initio , Doped Cr2O3
Citation
CAREY, J. J., LEGESSE, M. & NOLAN, M. 2016. Low Valence Cation Doping of Bulk Cr2O3: Charge Compensation and Oxygen Vacancy Formation. The Journal of Physical Chemistry C, 120 (34), 19160-19174. doi:10.1021/acs.jpcc.6b05575
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This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/full/10.1021/acs.jpcc.6b05575