Perovskite La0.3Sr0.7Fe0.7Cr0.3O3−δ Catalysis Raises the Bar: Preventing Unwanted Near‐Surface Sr Segregation and SrCO3 Precipitation

Abstract Sr surface segregation (SSS) in perovskite materials is a main factor causing efficiency degradation of solid oxide fuel cells (SOFC's), and therefore can affect the La 0.3 Sr 0.7 Fe 0.7 Cr 0.3 O 3− δ perovskite, which is known as a compatible anode and cathode in a reversible and symmetric SOFC. As a result of segregation, the atomic rearrangements in the near‐surface environment are likely to generate additional phases to the original one such as strontium carbonate (SrCO 3 ) at high CO 2 pressure. In the current work, first principal calculations are carried out for modeling the initial formation of SrCO 3 after Sr segregation in LSFCr with CO 2 presence. It is found that the tendency of CO 2 to participate in SrCO 3 phase formation is a competing reaction to its reduction to CO on the LSFCr material, and O vacancies are needed not only to improve CO 2 reduction but also to block the competing reaction of SrCO 3 adsorption. Therefore, LSFCr successfully “raises the bar” of CO 2 reduction catalytic efficiency by preventing unwanted Sr segregation at high concentrations of surface oxygen vacancies.