The critical role of A, B-site cations and oxygen vacancies on the OER electrocatalytic performances of Bi0.15Sr0.85Co1−xFexO3−δ (0.2 ≤ x ≤ 1) perovskites in alkaline media

Development of perovskite-type electrocatalysts with high activity, excellent durability and affordable cost provides a promising solution to promote commercialization of clean energy technologies. Here we prepared Bi 0.15 Sr 0.85 Co 1− x Fe x O 3−δ ( x  = 0.2, 0.4, 0.6, 0.8, 1) perovskites by the conventional solid-state reaction route, and investigated their OER electrocatalytic activity and durability in 0.1 M KOH solution to reveal the critical role of A, B-site cations and oxygen vacancies. Results show the OER activity decreases with increasing x . The optimum composition, BiSC 0.8 F 0.2 , presents impressive electrocatalytic performances with low overpotential (330 mV on rotation disk electrode, and 283 mV on carbon paper electrode at 10 mA/cm 2 ) and excellent long-time durability showing a small increase in the overpotential of 17 mV in 167.5 h. Comprehensive analysis and discussion on the bulk and surface properties reveal the critical role of A, B-site cations and oxygen vacancies on OER, and interrelations of Co 2+ fraction, oxygen non-stoichiometry and the OER overpotential have been established. Most importantly, a highly A-site deficient surface layer is found on the as-synthesized perovskite, which facilitate OER by exposing more active B-site cations. This work not only reports a promising OER electrocatalyst with high activity and superior durability, but also provides perspectives on relational design for highly efficient and stable perovskite electrocatalysts for OER using solid-state reaction method.