© 2017 by the authors. Licensee MDPI, Basel, Switzerland. Improving the activity of catalysts for the oxygen evolution reaction (OER) requires a detailed understanding of the surface chemistry and structure to deduce structure-function relationships (descriptors) for fundamental insight. We chose epitaxial (100)-oriented La 0.6 Sr 0.4 Mn 1 −δ O 3 (LSMO) thin ﬁlms as a model system with high electrochemical activity comparable to (110)-oriented IrO 2 to investigate the effect of Mn off-stoichiometry on both catalytic activity and stability. Extensive structural characterization was performed by microscopic and spectroscopic methods before and after electrochemical characterization using rotating ring-disk studies. Stoichiometric LSMO had the highest activity, while both Mn deﬁciency and excess reduced the catalytic activity. Furthermore, all samples preserved the crystal structure up to the very surface. Mn excess improved the long-term activity, and we hypothesize that excess Mn stabilizes the surface chemistry during catalysis. Our data show that the defect chemistry should be considered when designing catalysts with enhanced activity and rugged stability.
Scholz, J., Risch, M., Wartner, G., Luderer, C., Roddatis, V., & Jooss, C. (2017). Tailoring the oxygen evolution activity and stability using defect chemistry. Catalysts, 7(5). https://doi.org/10.3390/catal7050139