Extrinsic Fe3+ Stabilized La1-XSrxCoO3-? Thin Film Cathode for Enhanced Electrochemical Performance

Perovskite-based La0.6Sr0.4CoO3-d (LSC) is considered as one of the most promising electrode materials for solid oxide fuel cells (SOFCs). The broad application is, however hindered by its insufficient stability and reactivity at operating conditions. In this study, extrinsic Fe3+ decoration was applied to enhance the electrochemical performance of LSC thin-film electrodes by nearly 4 times. Time-of-flight secondary ion mass spectrometry indicated that the extrinsic Fe3+ can incorporate into LSC lattice and form a thermodynamically preferred (La, Sr)x(Co, Fe)yO3-d transition phase in the near surface region, thus improving its chemical stability against Sr segregation. X-ray photoelectron spectroscopy suggested the incorporation of Fe can lead to a ~0.2 eV downshift in LSC valance band and facilitate the formation of oxygen vacancies, thus enhancing electrode reactivity. These results can help us understand the mechanism of surface modification, and provide guidance for the rational design of more applicable SOFC electrode materials with higher reactivity and durability.