The development of efficient and stable oxygen reduction reaction (ORR) electrocatalysts in seawater electrolyte is the key to realizing marine resource utilization and expanding metal-air battery applications. Herein, defect-rich Fe-doped Co nanoparticles encapsulated by N-doped hierarchical carbon (D-_FeCo@NHC) are rationally designed and synthesized. It is worth mentioning that the Fe doping helps to promote the generation of metal defect and adjust the electronic structure of D-_FeCo@NHC. Density functional theory (DFT) demonstrate that the metal defect and carbon defect jointly optimize the d-band center of D-_FeCo@NHC. As a result, in alkaline seawater electrolyte, D-_FeCo@NHC display a half-wave potential of 0.874 V, and the assembled liquid Zn-air battery exhibit a high peak power density (173 mW cm⁻²) and ultra-long cycling stability (over 800 h). This work highlights the defect engineering in the construction of seawater-based oxygen reduction electrocatalysts, which provide a significant and promising approach for seawater-based metal-air cathode materials.

在海水电解液中开发高效稳定的氧还原反应（ORR）电催化剂是实现海洋资源利用和扩大金属空气电池应用的关键。_{在此，合理设计和合成了由 N 掺杂分级碳 (D- Fe} Co@NHC)包裹的富含缺陷的 Fe 掺杂 Co 纳米粒子。值得一提的是，Fe掺杂有助于促进金属缺陷的产生，调整D- _Fe Co@NHC的电子结构。密度泛函理论 (DFT) 表明金属缺陷和碳缺陷共同优化了D- _Fe Co@NHC的d带中心。因此，在碱性海水电解液中，D- _FeCo@NHC 的半波电位为 0.874 V，组装的液体锌空气电池具有高峰值功率密度（173 mW cm ^-2）和超长循环稳定性（超过 800 小时）。这项工作突出了海水基氧还原电催化剂构建中的缺陷工程，为海水基金属-空气阴极材料提供了一种重要且有前景的方法。