The development of low-cost and highly efficient single-atom oxygen reduction catalysts to replace platinum for fuel cells and metal–air cells is highly desirable but remains challenging. Herein, we report the fabrication of isolated single-atom Fe anchored on porous nitrogen-doped carbon from the pyrolysis of a well-designed solely Fe-tetrapyridophenazine coordination complex. The N-rich bridging ligand, tetrapyridophenazine (tpphz) is first employed as a spatial isolation agent of Fe that suppresses its aggregation during high temperature pyrolysis, resulting in highly reactive and stable single-atom Fe ORR catalysts. The catalyst shows remarkable ORR activity with a half-wave potential of 0.863 V versus the reversible hydrogen electrode (RHE) (21 mV more positive than that of commercial 20 wt% Pt/C) and excellent durability in 0.1 M KOH. Whereas in acidic media, the Fe single atoms also demonstrate ORR activity comparable to and stability much higher than those of Pt/C. Notably, Zn–air cells made using the as-prepared catalyst as the cathode provide a high open circuit voltage (1.53 V) and gravimetric energy density (947 W h kg⁻¹), which are higher than commercial Pt/C based Zn–air cells (1.50 V and 828 W h kg⁻¹). This work will open a new avenue to design single-atom catalysts for clean renewable energy storage and conversion devices.

中文翻译：

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合理设计的Fe-tetrapyridophenazine络合物：一个有前途的前体为在高功率锌-空气电池的有效的氧还原反应的单原子Fe催化剂†

迫切需要开发低成本，高效的单原子氧还原催化剂来代替铂金，以替代燃料电池和金属-空气电池，但仍具有挑战性。在这里，我们报道了由精心设计的单一Fe-四吡啶并吩嗪配位配合物的热解制备了锚定在多孔氮掺杂碳上的单原子Fe。富含N的桥联配体四吡啶并吩嗪（tpphz）首先被用作Fe的空间隔离剂，可在高温热解过程中抑制其聚集，从而产生高反应性和稳定的单原子Fe ORR催化剂。催化剂显示出显着的ORR活性，半波电势为0.863 V，相对于可逆氢电极（RHE）（比市售20 wt％Pt / C的正电极高21 mV），在0.1 M KOH中具有出色的耐久性。而在酸性介质中，Fe单原子也显示出与Pt / C相当的ORR活性，并且其稳定性远高于Pt / C。值得注意的是，使用所制备的催化剂作为阴极制成的Zn-空气电池具有很高的开路电压（1.53 V）和重量能量密度（947 W h kg ^-1），高于商业化的基于Pt / C的Zn-气室（1.50 V和828 W h kg ^-1）。这项工作将为设计用于清洁可再生能源存储和转换设备的单原子催化剂开辟一条新途径。