The key point to developing green and environmentally friendly zinc-air batteries is exploring efficient bifunctional electrocatalysts for oxygen reduction and evolution reactions (ORR and OER) on an air electrode. Herein, we reported a facile and green method for fabricating a bifunctional electrocatalyst of Co@N-CNT/rGO, which is composed of cobalt nanoparticles wrapped into nitrogen-doped carbon nanotubes growing on reduced graphene oxide. It is obtained by pyrolyzing a GO-wrapped two-dimension leaf-like zeolitic imidazolate framework. The Co@N-CNT/rGO-0.1 exhibits efficient catalytic activities for ORR and OER with a small Tafel slope. It benefits from the synergistic effect of the Co nanoparticle and N-CNT, the high conductivity of reduced graphene oxide and highly graphitizing carbon nanotubes, the great specific surface area, and suitable aperture size. Moreover, the Co@N-CNT/rGO-0.1 catalyst assembled primary zinc-air battery shows a high open-circuit voltage (1.43 V), a large peak power density (122 mW cm^–2), and an excellent specific capacity (855 mA h g_Zn^–1). In addition, the Co@N-CNT/rGO-0.1 assembly rechargeable zinc-air battery also displays an excellent cycling durability of 120 h at 5 mA cm^–2. According to the above results, our work provides a cost-effective strategy to scale-up and commercialize the bifunctional electrocatalysts for zinc-air battery application.

中文翻译：

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还原石墨烯氧化物上嵌入N掺杂碳纳米管中的钴纳米颗粒作为锌-空气电池的高效氧气催化剂

开发绿色环保的锌空气电池的关键是探索有效的双功能电催化剂，用于在空气电极上进行氧气还原和放出反应（ORR和OER）。本文中，我们报道了一种简便，绿色的Co @ N-CNT / rGO双功能电催化剂的制备方法，该催化剂由包裹在还原的氧化石墨烯上的氮掺杂碳纳米管包裹的钴纳米颗粒组成。它是通过热解GO包裹的二维叶状沸石咪唑酸盐骨架而获得的。Co@N-CNT/rGO-0.1具有小的Tafel斜率，对ORR和OER具有高效的催化活性。它受益于Co纳米颗粒和N-CNT的协同效应，还原的氧化石墨烯的高电导率和高度石墨化的碳纳米管，大的比表面积，和合适的光圈大小 而且，Co @ N-CNT / rGO-0.1催化剂组装的一次锌-空气电池显示出高开路电压（1.43 V），大峰值功率密度（122 mW cm）^–2）和出色的比容量（855 mA hg _Zn ^–1）。此外，Co @ N-CNT / rGO-0.1组件可充电锌空气电池在5 mA cm ^{–2的条件下}还具有120 h的出色循环耐久性。根据以上结果，我们的工作提供了一种具有成本效益的策略，可以扩大锌空气电池应用中的双功能电催化剂的规模并使其商业化。