Great efforts have been devoted to the development of bifunctional electrocatalysts to accelerate the sluggish kinetics of cathodic oxygen reduction/evolution reactions (ORR/OER) in zinc–air batteries (ZABs). Here we report a thermal evaporation–trapping synergistic strategy to fabricate a bifunctional electrocatalyst of flexible N-doped carbon fiber cloth loaded with both CoFe-oxide nanoparticles and single-atom Co/Fe–N_x sites, in which the thermal evaporation process functions in both downsizing CoFe-oxide nanoparticles and trapping the evaporated Co/Fe species to generate Co/Fe–N_x sites. The obtained flexible electrocatalyst, directly serving as an oxygen electrode, displays a small potential gap of 0.542 V for the OER/ORR, large peak power densities (liquid-state ZAB: 237.4 mW cm⁻²; solid-state ZAB: 141.1 mW cm⁻²), and excellent charge–discharge cycling stability without decay after working more than 770 hours. Furthermore, in situ Raman spectroscopy characterization and theoretical calculations reveal that CoFe₂O₄ species is responsible for the OER while atomic Fe/Co sites play a key role in the ORR.

中文翻译：

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一种热蒸发-捕获策略，用于合成用于可充电锌-空气电池的灵活而坚固的氧电催化剂


人们投入了大量精力开发双功能电催化剂，以加速锌-空气电池 （ZAB） 中阴极氧还原/析出反应 （ORR/OER） 的缓慢动力学。在这里，我们报道了一种热蒸发-捕获协同策略，以制造一种柔性 N 掺杂碳纤维布的双功能电催化剂，该催化剂负载有 CoFe 氧化物纳米颗粒和单原子 Co/Fe-N_x 位点，其中热蒸发过程的作用是缩小 CoFe 氧化物纳米颗粒的尺寸并捕获蒸发的 Co/Fe 物质以产生 Co/Fe-N_x网站。所获得的柔性电催化剂直接用作氧电极，对 OER/ORR 显示出 0.542 V 的小电位间隙、大峰值功率密度（液态 ZAB：237.4 mW ^cm-2;固态 ZAB：141.1 mW ^cm-2）和出色的充放电循环稳定性，工作超过 770 小时后无衰减。此外，原位拉曼光谱表征和理论计算表明，CoFe₂O₄ 物质负责 OER，而原子 Fe/Co 位点在 ORR 中起关键作用。