Bimetallic ZIFs-derived electrospun carbon nanofiber membrane as bifunctional oxygen electrocatalyst for rechargeable zinc-air battery

The recharged zinc-air battery (ZAB) has drawn significant attention owing to increasing requirement for energy conversion and storage devices. Fabricating the efficient bifunctional oxygen catalyst using a convenient strategy is vitally important for the rechargeable ZAB. In this study, the bimetallic ZIFs-containing electrospun (ES) carbon nanofibers membrane with hierarchically porous structure was prepared by coaxial electrospinning and carbonization process, which was expected to be a bifunctional electrocatalyst for ZABs. Owing to the formed dual single-atomic sites of Co–N4 and Zn–N4, the obtained ES-Co/Zn-CNZIF exhibited the preferable performance toward oxygen reduction reaction (ORR) with E1/2 of 0.857 V and JL of 5.52 mA cm−2, which were more than Pt/C. Meanwhile, it exhibited a marked oxygen evolution reaction (OER) property with overpotential of 462 mV due to the agglomerated metallic Co nanoparticles. Furthermore, the ZAB based on the ES-Co/Zn-CNZIF carbon nanofibers membranes delivered peak power density of 215 mW cm−2, specific capacity of 802.6 mA h g−1, and exceptional cycling stability, far larger than Pt/C+RuO2-based ZABs. A solid-state ZAB based on ES-Co/Zn-CNZIF showed better flexibility and stability with different bending angles.