A High-Performance Ruddlesden–Popper Perovskite for Bifunctional Oxygen Electrocatalysis

Highly active and stable bifunctional materials for the oxygen evolution/reduction reaction (OER/ORR) are critical for developing high-performance metal–air batteries and fuel cells. This study demonstrates the significantly enhanced electrocatalytic activity of a Ruddlesden–Popper (RP) perovskite (An+1BnO3n+1, n = 3) as a bifunctional material [i.e., RP-LaSr3(Co0.5Fe0.5)3O10−δ] for oxygen electrocatalysis via an optimal doping strategy. The improved performance mainly benefits from the enhanced oxygen vacancies, the facile oxygen release and incorporation abilities, the synergistic interplay of Co and Fe together with the increased amounts of adsorbed OH–/O2, and the highly oxidative O22–/O–. The more positive onset potential (Eonset) and the highest half wave potential (E1/2) of RP-LaSr3(Co0.5Fe0.5)3O10−δ imply a better ORR activity relative to those of the benchmark Ba0.5Sr0.5Co0.8Fe0.2O2.59 (BSCF) and the widely referred cubic perovskite (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ (CP-LSCF). Furthermore, this material enables the electrochemical reduction of O2 by 4e– to OH– with an impressive stability. More importantly, RP-LaSr3Co1.5Fe1.5O10−δ shows a largely narrowed potential gap (ΔE) and achieves its minimum value of 0.91 V, remarkably smaller than those of CP-LSCF (1.01 V), BSCF (1.04 V), and most of the state-of-the-art bifunctional materials. This study paves an attractive way to accurately fabricate RP-type perovskites as highly efficient and stable materials for bifunctional oxygen electrocatalysis.