Highly stable and porous triple perovskite oxide as a bifunctional electrocatalyst for rechargeable Zn-air batteries

• Triple perovskite oxide is introduced as a novel bifunctional catalyst for metal-air batteries. • Stacked perovskite blocks with repeated lanthanide layers create lattice distortion and abundant oxygen vacancies. • LSCFO triple perovskite excels in ORR/OER due to increased oxygen vacancies. • DFT reveals that reduced O 2p-metal 3d hybridization lowers charge transfer resistance, improving catalysis. • The robust structure and high catalytic activity of LSCFO provide prolonged cycling stability in Zn-air batteries. • Earth-abundant elements and scalable synthesis position this catalyst as a promising noble metal alternative. The depletion of fossil fuels and associated greenhouse effects pose critical challenges for modern power generation. Zinc-air batteries offer a promising solution due to their natural abundance, safety, and low cost. In this study, triple perovskite-based electrocatalysts were synthesized via a sol–gel method to address the need for stable, cost-effective, and active catalysts. Among them, La 1.5 Sr 1.5 Co 1.5 Fe 1.5 O 9−δ (LSCFO) exhibited outstanding bifunctional activity for the oxygen reduction (ORR) and oxygen evolution reactions (OER), with a potential gap (ΔE) of 0.73 V at 10 mA cm −2 . Density functional theory (DFT) calculations revealed optimized adsorption energies, enhanced charge transfer capabilities, and the formation of oxygen vacancies due to the partial substitution of A- and B-site elements by Sr and Fe. In zinc-air batteries, LSCFO achieved a high specific energy density of 753.1 mAh g −1 , excellent discharge and charge voltages, and stability over 1100 h. These results position LSCFO as a comparatively cost-effective, scalable alternative to precious metal catalysts for zinc-air batteries.