材料科学
塔菲尔方程
催化作用
电解质
阴极
化学工程
碳纤维
纳米技术
电极
电化学
复合材料
化学
物理化学
复合数
有机化学
工程类
作者
Yang Liu,Xu Zhang,Lingxiao Yu,Jianhua Hou,Zhen Zhou,Ruitao Lv
标识
DOI:10.1002/adma.202105410
摘要
Noble-metal-free, durable, and high-efficiency electrocatalysts for oxygen reduction and evolution reaction (ORR/OER) are vital for rechargeable Zn-air batteries (ZABs). Herein, a flexible and free-standing carbon fiber membrane immobilized with atomically dispersed Fe-N4 /C catalysts (Fe/SNCFs-NH3 ) is synthesized and used as air cathode for ZABs. The intertwined fibers with hierarchical nanopores facilitate the gas transportation, electrolyte infiltration and electron transfer. The large specific surface area exposes a high concentration of Fe-N4 /C sites embedded in the carbon matrix. Modulation of local atomic configurations by sulfur doping in Fe/SNCFs-NH3 catalyst leads to excellent ORR and enhanced OER activities. The as-synthesized Fe/SNCFs-NH3 catalyst demonstrates a positive half-wave potential of 0.89 V and a small Tafel slope of 70.82 mV dec-1 , outperforming the commercial Pt/C (0.86 V/94.74 mV dec-1 ) and most reported M-Nx /C (M = Fe, Co, Ni) catalysts. Experimental characterizations and theoretical calculations uncover the crucial role of S doping in regulating ORR and OER activities. The liquid-state ZABs with Fe/SNCFs-NH3 catalyst as air cathode deliver a large peak power density of 255.84 mW cm-2 and long-term cycle durability over 1000 h. Solid-state ZAB shows stable cycling at various flat/bent/flat states, demonstrating great prospects in flexible electronic device applications.
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