In the present work, an iron-cobaltite spinel supported on N-containing carbon nanofibers (CNFs) shows a remarkable activity for the oxygen evolution reaction (OER) in alkaline solution, with an overpotential (η_10mAcm^-2) of 130 mV, one of the lowest values in literature so far. This material is also an excellent catalyst for the oxygen reduction reaction (ORR), what leads to an extraordinary reversible behavior (ΔE = E_OER – E_ORR=480 mV), being an economic and easy scalable candidate for the air electrode of metal-air batteries or for electrochemical devices where the oxygen evolution or the oxygen reduction is involved. In the present research, Fe partially replaces Co atoms in the Co₃O₄ spinel structure to obtain a more economically feasible material, leading to a FeCo₂O₄/CNF, by using an electrospinning preparation procedure previously adopted for the Co₃O₄/CNF synthesis. The substitution of iron in the Co₃O₄/CNF spinel entails an outstanding onset potential toward the OER of 1.36 V vs. reversible hydrogen electrode, which is 120 mV lower compared with the pure spinel (Co₃O₄/CNF). An optimal distribution of the FeCo₂O₄ particles on the CNF surface, with 3-nm-size particles, allows exposing abundant active sites, mainly Co³⁺ and Fe³⁺, responsible for the enhanced activity toward the OER, and Fe-N_x moieties and N-sites (N-graphitic/pyridinic), more active for the ORR. Besides, FeCo₂O₄/CNF shows a well-developed porous structure, favoring the mass transfer, a parameter particularly important for the ORR. To assess the stability of the catalysts for rechargeable alkaline metal-air batteries, cycling operation and chronopotentiometric experiments are carried out, showing a stable potential for 24 h.

在目前的工作中，负载在含N的碳纳米纤维（CNF）上的铁钴尖晶石对碱性溶液中的氧释放反应（OER）表现出显着的活性，其超电势（_{η10mAcm ^-2}）为130 mV，一个迄今为止文学中最低的值。这种材料还是氧还原反应（ORR）的出色催化剂，可导致异常的可逆行为（ΔE= E _OER – E _{ORR =} 480 mV），是金属-空气电极的经济且易于扩展的候选材料。空气电池或用于涉及氧气释放或氧气还原的电化学设备。在本研究中，Fe部分替代了Co ₃ O ₄中的Co原子通过使用先前为Co ₃ O ₄ / CNF合成所采用的电纺丝制备程序，获得尖晶石结构以获得更经济可行的材料，从而生成FeCo ₂ O ₄ / CNF 。与可逆氢电极相比，Co ₃ O ₄ / CNF尖晶石中铁的替代使OER相对于可逆氢电极的OER为1.36 V，这比纯尖晶石（Co ₃ O ₄ / CNF）低120 mV 。FeCo ₂ O ₄颗粒在CNF表面的最佳分布（粒径为3 nm）可以暴露出大量的活性位点，主要是Co ³⁺和Fe³⁺负责增强对OER的活性，以及​​Fe-N _x部分和N位（N-石墨/吡啶），对ORR更具活性。此外，FeCo ₂ O ₄ / CNF显示出发达的多孔结构，有利于传质，这是对ORR特别重要的参数。为了评估可充电碱性金属-空气电池催化剂的稳定性，进行了循环操作和计时电位实验，显示24小时的稳定电位。