Construction of robust protective cover on delicate active sites is a frequently-used scheme to enhance the durability of air-cathode catalyst working in harsh environment, thus the lifespan of rechargeable Zinc-air batteries (ZABs). Paradoxically, this would degrade the activity due to the constricted accessibility of active sites to reactants. Herein, carbon nanotubes with abundant mesoporous defects and Fe-N species were elaborately designed to be multifunctional protective armor to encapsulate NiFe nano-alloys (NiFe@CNTs/Fe-N) for bifunctional oxygen electrocatalyst. In/ex-situ spectroscopy analysis and theoretical calculations reveal that the constructed mesoporous carbon defects effectively facilitate the multiphase mass transfer and the oxygen evolution reaction kinetics via strong electrons coupling with packaged NiFe nano-alloys. Meanwhile, the synchronously introduced Fe-N moieties could serve as oxygen reduction active sites. Thus, the obtained NiFe@CNTs/Fe-N hybrid electrocatalyst simultaneously exhibits remarkable bifunctional catalytic activity (E=0.86/E=1.59 V vs RHE) and durability over 450 h in the chronoamperometric test at 1.59 V, endowing the assembled Zn-air batteries (ZABs) with a high power density (150 mW cm) and lifespan (307 h), much better than that employing benchmark Pt/C+RuO mixed catalyst. This work demonstrates an innovative design route for the multifunctional armor to concurrently enhance the durability, activity and robustness of air-cathode-catalyst for ZABs.

中文翻译：

---

多功能碳装甲：同步提高过渡金属合金基混合催化剂的氧反应动力学、传质动力学和稳健性


在脆弱的活性位点上构建坚固的保护盖是一种常用的方案，以提高空气阴极催化剂在恶劣环境下工作的耐久性，从而延长可充电锌空气电池（ZAB）的使用寿命。矛盾的是，由于反应物活性位点的可及性受到限制，这会降低活性。在此，具有丰富介孔缺陷和Fe-N物质的碳纳米管被精心设计成多功能防护装甲，以封装用于双功能氧电催化剂的NiFe纳米合金（NiFe@CNTs/Fe-N）。原位/异位光谱分析和理论计算表明，所构建的介孔碳缺陷通过与封装的NiFe纳米合金的强电子耦合，有效促进了多相传质和析氧反应动力学。同时，同步引入的Fe-N部分可以作为氧还原活性位点。因此，所获得的NiFe@CNTs/Fe-N杂化电催化剂在1.59V的计时电流测试中同时表现出显着的双功能催化活性（E=0.86/E=1.59V vs RHE）和超过450小时的耐久性，赋予组装的锌-空气电池（ZAB）具有高功率密度（150mWcm）和寿命（307小时），远优于采用基准Pt/C+RuO混合催化剂的电池。这项工作展示了多功能装甲的创新设计路线，可同时增强 ZAB 空气阴极催化剂的耐用性、活性和鲁棒性。