The construction of transition metal-based catalysts with high activity and stability has been widely regarded as a promising method to replace the precious metal Pt for oxygen reduction reaction (ORR). Herein, we synthesized CoFe alloy nanoparticle-embedded N-doped graphitic carbon (CoFe/NC) nanostructures as ORR electrocatalysts. The ZIF-67 (zeolitic imidazolate framework, ZIF) nanocubes were first synthesized, followed by an introduction of Fe²⁺ ions to form CoFe-ZIF precursors via a simple ion-exchange route. Subsequently, the CoFe/NC composites were synthesized through a facile pyrolysis strategy. The ORR activity and the contents of cobalt and iron could be effectively adjusted by controlling the solution concentration of Fe²⁺ ions used for the ion exchange and the pyrolysis temperature. The CoFe/NC-0.2-900 composite (synthesized with 0.2 mmol of FeSO₄·7H₂O at a pyrolysis temperature of 900°C) exhibited ORR activity that was superior to the other samples owing to a synergistic effect of the bimetal, especially considering the extremely high limiting current density of 6.4 mA cm⁻² compared with that of Pt/C (5.1 mA cm⁻²). Rechargeable Zn-air batteries were assembled employing CoFe/NC-0.2-900 and NiFeP/NF (NiFeP supported on nickel foam (NF)) as the catalysts for the discharging and charging processes, respectively, The above materials achieved reduced discharging and charging platforms, high power density, and prolonged cycling stability compared with conventional Pt/C+RuO₂/C catalysts.

具有高活性和稳定性的过渡金属基催化剂的构建已被广泛认为是一种替代贵金属Pt进行氧还原反应（ORR）的有前途的方法。在这里，我们合成了嵌入CoFe合金纳米粒子的N掺杂石墨碳（CoFe / NC）纳米结构作为ORR电催化剂。在ZIF-67（沸石咪唑酯骨架，ZIF）纳米立方体首先合成，随后介绍的Fe ²⁺离子形成的CoFe-ZIF前体通过一个简单的离子交换路线。随后，通过简便的热解策略合成了CoFe / NC复合材料。通过控制Fe ²⁺的溶液浓度，可以有效地调节ORR活性以及钴和铁的含量离子用于离子交换和热解温度。CoFe / NC-0.2-900复合材料（在900°C的热解温度下用0.2 mmol的FeSO ₄ ·7H ₂ O合成）表现出的ORR活性优于其他样品，这归因于双金属的协同作用，特别是考虑到与Pt / C（5.1 mA cm ^-2）相比极高的6.4 mA cm ^-2极限电流密度）。分别使用CoFe / NC-0.2-900和NiFeP / NF（镍泡沫（镍泡沫支撑）上的NiFeP）作为放电和充电过程的催化剂组装可充电Zn-空气电池，上述材料实现了减少的放电和充电平台与传统的Pt / C + RuO ₂ / C催化剂相比，具有更高的功率密度和更长的循环稳定性。