The development of bifunctional catalysts with a delicate structure, high efficiency, and good durability for the oxygen evolution reaction (ORR) and oxygen evolution reaction (OER) is crucial to renewable Zn–air batteries. In this work, Co_0.7Fe_0.3 alloy nanoparticles (NPs) confined in N-doped carbon with a yolk–shell structure in multi-beaded fibers were prepared as a bifunctional electrocatalyst. The confinement structure was composed of an N-doped graphitized carbon shell and a core formed by numerous Co_0.7Fe_0.3 NPs, and was evenly threaded into a one-dimensional fiber. Moreover, this distinctive hierarchical structure featured abundant mesopores, a high BET surface area of 743.8 m² g⁻¹, good electronic conductivity, and uniformly distributed Co_0.7Fe_0.3/Co(Fe)–N_x coupling active sites. Therefore, the experimentally optimized Co_0.7Fe_0.3@NC_2:1-800 showed excellent OER performance (overpotential reached 314 mV at 10 mA cm⁻²) that far exceeded RuO₂ (353 mV), and good ORR catalytic performance (half-wave potential of 0.827 V) comparable to Pt/C (0.818 V). Impressively, the Co_0.7Fe_0.3@NC_2:1-800 Zn–air battery delivered a higher open circuit voltage of 1.449 V, large power density of 85.7 mW cm⁻², and outstanding charge–discharge cycling stability compared with the commercial RuO₂ + 20 wt% Pt/C catalyst. This work provides new ideas for the structural design of electrocatalysts and energy conversion systems.

中文翻译：

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Co0.7Fe0.3 NP限制在卵黄壳掺N碳中：工程化多珠纤维作为锌空气电池的高效双功能电催化剂

开发具有精细结构，高效且对氧气析出反应（ORR）和氧气析出反应（OER）具有良好耐久性的双功能催化剂，对于可再生Zn-空气电池至关重要。在这项工作中，准备将Co _0.7 Fe _0.3合金纳米颗粒（NPs）限制在N掺杂的碳中，并在多珠状纤维中采用卵黄壳结构作为双功能电催化剂。该限制结构由N掺杂的石墨化碳壳和由众多Co _0.7 Fe _0.3 NPs形成的核组成，并均匀地穿入一维纤维。此外，这种独特的层次结构具有丰富的中孔，BET表面积高达743.8 m ² g ^-1，良好的电导率和均匀分布的Co _0.7 Fe _0.3 / Co（Fe）–N _x耦合活性位。因此，实验优化钴_0.7铁_0.3 @NC _2：1 - 800表现出优异的性能OER（超电势达到314毫伏在10mA厘米^-2），其远远超过的RuO ₂（353毫伏），以及良好的ORR催化能力（半波电位为0.827 V）相当于Pt / C（0.818 V）。令人印象深刻，将Co _0.7铁_0.3 @NC _2:1 - 800与商用RuO ₂ + 20 wt％Pt / C催化剂相比，锌-空气电池具有更高的1.449 V开路电压，85.7 mW cm ^-2的大功率密度以及出色的充放电循环稳定性。这项工作为电催化剂和能量转换系统的结构设计提供了新思路。