Non-platinum group metal (non-PGM) catalysts, constructed from cheap and abundant carbon, nitrogen and 3d transition metals as bricks, have been regarded as the most promising candidates for the oxygen reduction reaction (ORR) in fuel cells and metal–air batteries. In this work, well-defined carbon interpenetrating networks have been fabricated by controllable pyrolysis carbonization of polyaniline (PANI) nanotubes epitaxially grown using a dodecahedral zeolitic imidazolate framework (ZIF-8) with FeCl₃ at 900 °C. The interpenetrating networks feature a stable free-standing three-dimensional structure, composed of carbon nanotubes (CNTs) derived from PANI and carbon nanoparticles (CNPs) from ZIF-8. In KOH solution, the synthesized catalyst with an interpenetrating network structure shows a superior ORR activity with a half-wave potential of 0.95 V (vs. RHE) and a mass activity of 0.046 A mg_cat⁻¹ at 0.9 V (vs. RHE), which are much better than those of most Fe–N–C reported and commercial Pt/C (0.84 V vs. RHE, 0.044 A mg_pt⁻¹). Moreover, it also displays superior performance and long-term durability in a Zn–air full battery, outperforming recently reported carbon-based catalysts. It was determined from DFT calculation results that there exist remarkably increased at-edge Fe–N_x moieties at the boundaries and interfaces in the chemically connected CNT/CNP composites. These edge moieties are the main active sites that should be responsible for the substantially improved performances. Therefore, the design of carbon/carbon composites with a smart nanophase structure is an effective strategy for developing next-generation non-PGM catalysts.

中文翻译：

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杂原子掺杂的碳互穿网络：实现燃料电池非PGM催化剂最佳性能的路标

由廉价和丰富的碳，氮和3d过渡金属作为砖块构造的非铂族金属（non-PGM）催化剂被视为燃料电池和金属-空气中氧还原反应（ORR）的最有希望的候选者电池。在这项工作中，通过使用十二烷基沸石咪唑酸盐骨架（ZIF-8）和FeCl ₃外延生长的聚苯胺（PANI）纳米管的可控热解碳化，制造了定义明确的碳互穿网络。在900°C下。互穿网络具有稳定的独立式三维结构，该结构由PANI衍生的碳纳米管（CNT）和ZIF-8衍生的碳纳米颗粒（CNP）组成。在KOH溶液中，具有互穿网络结构的合成催化剂显示出优异的ORR活性，半波电势为0.95 V（相对于RHE），质量活性为0.046 A mg _cat ^-1，在0.9 V（相对于RHE） ，这要比大多数Fe–N–C和商业化的Pt / C要好得多（0.84 V vs. RHE，0.044 A mg _pt ^-1）。此外，它在Zn-空气充满电池中也显示出卓越的性能和长期耐久性，优于最近报道的碳基催化剂。从DFT计算结果可以确定，在化学连接的CNT / CNP复合材料的边界和界面处，边缘的Fe-N _x部分显着增加。这些边缘部分是主要的活性部位，应负责显着改善性能。因此，设计具有智能纳米相结构的碳/碳复合材料是开发下一代非PGM催化剂的有效策略。