Formation and Migration of Oxygen Vacancies in SrCoO3 and their effect on Oxygen Evolution Reactions

Hassan A. Tahini, Xin Tan, Udo Schwingenschlögl, Sean C. Smith

Research output: Contribution to journalArticlepeer-review

93 Scopus citations

Abstract

Perovskite SrCoO3 is a potentially useful material for promoting the electrocatalytic oxygen evolution reaction, with high activities predicted theoretically and observed experimentally for closely related doped perovskite materials. However, complete stoichiometric oxidation is very difficult to realize experimentally – in almost all cases there are significant fractions of oxygen vacancies present. Here, using first principles calculations we study oxygen vacancies in perovskite SrCoO3 from thermodynamic, electronic and kinetic points of view. We find that an oxygen vacancy donates two electrons to neighboring Co sites in the form of localized charge. The formation energy of a single vacancy is very low and estimated to be 1.26 eV in the dilute limit. We find that a vacancy is quite mobile with a migration energy of ~0.5 eV. Moreover, we predict that oxygen vacancies exhibit a tendency towards clustering which is in accordance with the material’s ability to form a variety of oxygen-deficient structures. These vacancies have a profound effect on the material’s ability to facilitate OER, increasing the overpotential from ~0.3 V for the perfect material to ~0.7 for defective surfaces. A moderate compressive biaxial strain (2%) is predicted here to increase the surface oxygen vacancy formation energy by ca. 30%, thus reducing the concentration of surface vacancies and thereby preserving the OER activity of the material.
Original languageEnglish (US)
Pages (from-to)5565-5570
Number of pages6
JournalACS Catalysis
Volume6
Issue number8
DOIs
StatePublished - Jul 27 2016

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This research was undertaken with the assistance of UNSW Australia SPF01 funding (SCS). We
acknowledge generous allocations of supercomputing time at the Pawsey Supercomputing Centre via the
Australian National Computational Merit Allocation Scheme (NCMAS project fr2) and the Energy and
Resources Merit Allocation Scheme of the Pawsey Supercomputing Centre (project pawsey0111).
Additional computational resources were provided by KAUST on the Shaheen II supercomputer.

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