FeNi alloys encapsulated in N-doped CNTs-tangled porous carbon fibers as highly efficient and durable bifunctional oxygen electrocatalyst for rechargeable zinc-air battery

It remains a great challenge to develop high-efficient, low-cost and robustly stable bifunctional oxygen electrocatalysts for rechargeable metal-air batteries. Herein, we report a promising electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The electrocatalysts are composed of nanostructured FeNi alloy nanoparticles inlaid on N-doped carbon nanotubes (CNTs)-tangled porous carbon fibers (FeNi/N-CPCF). Benefiting from its hierarchically porous structures with bamboo-like CNTs grafted, and strong synergetic coupling between FeNi alloys and N-doped carbon species, the as-prepared FeNi/N-CPCF-950 demonstrates a half-wave potential of 0.867 V for ORR and a low operating potential of 1.585 V at 10 mA cm−2 for OER in 0.1 M KOH, outperforming commercial Pt/C and RuO2. Moreover, such bifunctioal catalyst endows the homemade zinc-air batteries with a high energy efficiency of 61.5%, small charge-discharge voltage gap of 0.764 V, and outstanding cycling performance (640 h, 960 cycles) at 10 mA cm−2 under ambient conditions.