Sc and Nb Dopants in SrCoO3 Modulate Electronic and Vacancy Structures for Improved Water Splitting and SOFC Cathodes
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractSrCoO3 is a promising material in the field of electrocatalysis. Difficulties in synthesising the material in its cubic phase have been overcome by doping it with Sc and Nb ions [Mater. Horiz.2015, 2, 495–501]. Using ab initio calculations and special quasi random structures we undertake a systematic study of these dopants in order to elucidate the effect of doping on electronic structure of the SrCoO3 host and the formation of oxygen vacancies. We find that while the overall electronic structure of SrCoO3 is preserved, increasing the Sc fraction leads to a decrease of electrical conductivity, in agreement with earlier experimental work. For low Sc and Nb doping fractions we find that the oxygen vacancy formation increases relative to undoped SrCoO3. However, as the dopants concentration is increased the vacancy formation energy drops significantly, indicating a strong tendency to accommodate high concentration of oxygen vacancies and hence non-stoichiometry. This is explained based on the electronic instabilities caused by the presence of Sc ions which weakens the B-O interactions as well as the increased degree of electron delocalization on the oxygen sublattice. Sc dopants also shift the p-band centre closer to the Fermi level, which can be associated with experimentally reported improvements in oxygen evolution reactions. These findings provide crucial baseline information for the design of better electrocatalysts for oxygen evolution reactions as well as fuel-cell cathode materials.
CitationTahini HA, Tan X, Zhou W, Zhu Z, Schwingenschlögl U, et al. (2017) Sc and Nb Dopants in SrCoO3 Modulate Electronic and Vacancy Structures for Improved Water Splitting and SOFC Cathodes. Energy Storage Materials. Available: http://dx.doi.org/10.1016/j.ensm.2017.01.005.
SponsorsThis 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.
JournalEnergy Storage Materials