Iron-based catalysts are considered highly promising as non-noble metal catalysts for oxygen electroreduction. However, the optimization of iron-based catalysts is limited by the well-designed carbon support and high-efficiency catalytic sites. Furthermore, achieving high production yield on an industrial scale while maintaining high performance would also be highly encouraged. Therefore, a dual-protection-exposure mechanism was employed for a hierarchical porous carbon (HPC) embedded with Fe–N4 sites (Fe–N4/HPC) catalysts, which were prepared through the ionothermal carbonization of Fe/ZnTBrPP@MgCl2 [5, 10, 15, 20-tetrakis (4′-bromophenyl) porphyrinato iron (FeTBrPP) mixed with ZnTBrPP on MgCl2·6H2O template]. Apart from self-protection-exposure of the Fe/ZnTBrPP itself, the hydrated salt template provided a secondary protection and exposure simultaneously. As a result, the Fe–N4/HPC retains more Fe–N4 sites and a larger BET surface, resulting in excellent ORR activity and durability in alkaline (0.922 V vs. RHE). Interestingly, under the conditions of using hydrated magnesium salt as a soft template, the yield rate of the Fe–N4/HPC significantly higher than the product without hydrated salt. Furthermore, the utilization of Fe–N4/HPC as the cathode in a zinc-air battery demonstrated remarkable performance, achieving an high peak power density (94 mW cm−2) and good stability.

中文翻译：

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用于有效氧还原的高产率含Fe–N4位点多孔碳电催化剂和锌空气电池的制备：双重保护-暴露机制的效果


铁基催化剂被认为是非常有前途的氧电还原非贵金属催化剂。然而，铁基催化剂的优化受到精心设计的碳载体和高效催化位点的限制。此外，在保持高性能的同时，在工业规模上实现高产量也将受到强烈鼓励。因此，对嵌入 Fe-N4 位 （Fe-N4/HPC） 催化剂的多级多孔碳 （HPC） 采用了双重保护-暴露机制，该催化剂是通过 Fe/ZnTBrPP@MgCl2 的离子热碳化制备的 [5， 10， 15， 20-tetrakis （4′-bromophenyl） porphyrinato iron （FeTBrPP） 与 ZnTBrPP 在 MgCl2·6H2O 模板上混合]。除了 Fe/ZnTBrPP 本身的自我保护暴露外，水合盐模板还同时提供了二次保护和暴露。因此，Fe-N4/HPC 保留了更多的 Fe-N4 位点和更大的 BET 表面，从而在碱性环境中具有出色的 ORR 活性和耐久性（0.922 V vs. RHE）。有趣的是，在使用水合镁盐作为软模板的条件下，Fe–N4/HPC 的产率明显高于未使用水合盐的产品。此外，在锌空气电池中使用 Fe-N4/HPC 作为阴极表现出卓越的性能，实现了高峰值功率密度 （94 mW cm-2） 和良好的稳定性。