A Durable Ruddlesden‐Popper Cathode for Protonic Ceramic Fuel Cells

Abstract Protonic ceramic fuel cells (PCFCs) have been proved as an efficient energy converter at intermediate temperatures. To accelerate the kinetics of the proton‐involved oxygen reduction reaction (p‐ORR), developing efficient and durable cathodes is of great importance for improving PCFCs. In this work, a new triple‐layered Ruddlesden‐Popper (R−P) structure oxide, Sr 3 EuFe 2.5 Co 0.5 O 10− δ (3‐SEFC 0.5 ), was developed as a potential single‐phase cathode for PCFCs, showing high oxygen non‐stoichiometry and desirable structural thermal stability. By employing this highly active and stable single‐phase cathode, the PCFC demonstrated unprecedented low polarization resistances and exceptionally great peak power densities, which were approximately 0.030 Ω cm 2 and 900 mW cm −2 measured at 700 °C, respectively. These findings not only manifest the effectiveness of optimal doping in improving the structural stability and electrocatalytic activity in the multi‐layered perovskite family, but also highlight the great potential of using multi‐layered R−P series oxides as highly active and durable catalysts for PCFCs.