Formation and Migration of Oxygen Vacancies in SrCoO3 and their effect on Oxygen Evolution Reactions
Type
ArticleKAUST Department
Computational Physics and Materials Science (CPMS)Material Science and Engineering Program
Physical Science and Engineering (PSE) Division
Date
2016-07-27Online Publication Date
2016-07-27Print Publication Date
2016-08-05Permanent link to this record
http://hdl.handle.net/10754/617509
Metadata
Show full item recordAbstract
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.Citation
Formation and Migration of Oxygen Vacancies in SrCoO 3 and their effect on Oxygen Evolution Reactions 2016 ACS CatalysisSponsors
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.Publisher
American Chemical Society (ACS)Journal
ACS CatalysisAdditional Links
http://pubs.acs.org/doi/abs/10.1021/acscatal.6b00937ae974a485f413a2113503eed53cd6c53
10.1021/acscatal.6b00937