In-situ construction of Ruddlesden-Popper/perovskite heterointerface induces efficient bifunctional oxygen electrocatalyst for rechargeable zinc-air batteries

• Hierarchical RP-PSNC/P-PNC nanofibers with core-shell structure are synthesized. • RP-PSNC/P-PNC displays efficient bifunctional catalytic activities. • The interfacial vacancies and hierarchical structure increase the catalytic activities. • RP-PSNC/P-PNC-based batteries exhibit excellent power density and durability. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the prerequisite reactions in rechargeable zinc-air batteries (ZABs), but their kinetics are usually slow. In order to develop energy-efficient ZABs, it is highly desirable to pursue bifunctional catalysts with the accelerated reaction kinetics and the reduced overpotentials. Transition metal oxides are expected as promising alternatives to replace noble metal-based catalysts, but their catalytic activities are still far from desirable. Herein, we propose a modified layer of Ruddlesden-Popper perovskite (Pr,Sr) 2 Ni 0.5 Co 0.5 O 4-δ (RP-PSNC) on the perovskite PrNi 0.5 Co 0.5 O 3-δ (P-PNC) nanofiber by a simple impregnation method, receiving a (Pr,Sr) 2 Ni 0.5 Co 0.5 O 4-δ / PrNi 0.5 Co 0.5 O 3-δ (RP-PSNC/P-PNC) heterostructured nanofibers. The RP-PSNC/P-PNC hybrid catalyst exhibits a small overpotential and an excellent stability due to the large number of vacancies in the two-phase interface. The RP-PSNC/P-PNC-based liquid rechargeable ZAB reaches a power density of 145 mW cm −2 , and 230 h of long-term cycle performance. When assembled into flexible ZABs, it can also reach a power density of 51 mW cm −2 and a stable open circuit voltage (∼1.35 V) for 44 h. These results indicate that the bifunctional electrocatalyst of heterostructured RP-PSNC/P-PNC provides a new path for the modification of perovskites through multi-phase catalysts system, and has great potential in rechargeable ZABs and other energy conversion devices.