Effective, rational design of innovative low-cost materials with high oxygen reduction reaction (ORR) catalytic activity at intermediate temperatures (ITs) requires greater understanding of the underlying reaction mechanisms of oxygen incorporation into solid oxide fuel cell (SOFC) cathodes [1-4].In this contribution, we discuss our first-principles study of ORR mechanism for two materials. First, we address the conventional SOFC cathode material, La0.75Sr0.25MnO3 (LSM) which, as a poor oxide ion conductor at ITs, limits the ORR catalysis to occur only at the triple phase boundary (where cathode, electrolyte, and gas meet). We then compare LSM to the new cathode material based on SrFe1.5Mo0.5O6-d(SFMO), which is very promising for IT-SOFCs thanks to its mixed ion-electron conductor (MIEC) nature [5]. For both materials, we focus on electrocatalytic processes involving O2 adsorption on the surface, dissociation, and, finally, O incorporation into the bulk material, paying attention to preferred adsorption sites and rate-limiting steps.Our results highlight the importance of oxygen-oxygen bond dissociation and of surface vacancies in both materials. A quantum mechanical analysis of the important electronic features driving these processes affords new insights into the roles of defects and transition metal additives in achieving efficient ORR catalysis.[1] Mu�oz-Garc�a, A. B.; Pavone, M.; Carter, E. A. Chem. Mater. 2011, 23, 4525�4536.[2] Pavone, M.; Ritzmann, A. M.; Carter, E. A. Energy Environ. Sci. 2011, 4, 4933�4937.?[3] Mu�oz-Garc�a, A. B.; Bugaris, D. E.; Pavone, M.; Hodges, J. P.; Huq, A.; Chen, F.; zur Loye, H.-C.; Carter, E. A. J. Am. Chem. Soc. 2012, 134, 6826�6833[4] Mu�oz-Garc�a, A. B.; Pavone, M.; Riztmann, A. M.; Carter, E. A. Phys. Chem. Chem. Phys. 2013, 15, 6250�6259.[5] Liu, Q.; Dong, X.; Xiao, G.; Zhao, F.; Chen, F. Adv. Mater. 2010, 22, 5478-5482.

Ab initio study of the oxygen reduction reaction at SOFC cathodes: State-of- the-art La(1-x)SrxMnO3 vs. the new SrFe(1+x)MoxO(6-d) mixed ion-electron conductor

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.