Oxygen Reduction Activity and Interfacial Structures of La0.8Sr0.2CoO3 at Initial Electrochemical Process in an Alkaline Solution (Supporting Information)

Oxygen reduction and evolution reactions (ORR and OER, respectively) of perovskite-type La0.8Sr0.2CoO3 were characterized using two-dimensional model electrodes with different reaction planes (001), (110), and (111). Synthesized by pulsed laser deposition, these thin (30 nm) and flat (roughness 0.8Sr0.2CoO3, and these changes are associated with forming oxygen defects during the initial electrochemical process. Furthermore, the La0.8Sr0.2CoO3 surface partially decomposed upon reacting with the aqueous solution, as clarified by hard X-ray photoemission spectroscopy. Therefore, the interfacial structures formed in the electrochemical reaction field is important for enhancing ORR and OER activities.