材料科学
静电纺丝
纳米纤维
催化作用
钴
化学工程
质子交换膜燃料电池
聚丙烯腈
阴极
碳纤维
碳纳米管
纳米技术
碳纳米纤维
聚合物
复合材料
有机化学
化学
物理化学
冶金
工程类
复合数
作者
Yanghua He,Hui Guo,Sooyeon Hwang,Xiaoxuan Yang,Zizhou He,Jonathan Braaten,S. Karakalos,Weitao Shan,Maoyu Wang,Hua Zhou,Zhenxing Feng,Karren L. More,Guofeng Wang,Dong Su,David A. Cullen,Ling Fei,Shawn Litster,Gang Wu
标识
DOI:10.1002/adma.202003577
摘要
Increasing catalytic activity and durability of atomically dispersed metal-nitrogen-carbon (M-N-C) catalysts for the oxygen reduction reaction (ORR) cathode in proton-exchange-membrane fuel cells remains a grand challenge. Here, a high-power and durable Co-N-C nanofiber catalyst synthesized through electrospinning cobalt-doped zeolitic imidazolate frameworks into selected polyacrylonitrile and poly(vinylpyrrolidone) polymers is reported. The distinct porous fibrous morphology and hierarchical structures play a vital role in boosting electrode performance by exposing more accessible active sites, providing facile electron conductivity, and facilitating the mass transport of reactant. The enhanced intrinsic activity is attributed to the extra graphitic N dopants surrounding the CoN4 moieties. The highly graphitized carbon matrix in the catalyst is beneficial for enhancing the carbon corrosion resistance, thereby promoting catalyst stability. The unique nanoscale X-ray computed tomography verifies the well-distributed ionomer coverage throughout the fibrous carbon network in the catalyst. The membrane electrode assembly achieves a power density of 0.40 W cm-2 in a practical H2 /air cell (1.0 bar) and demonstrates significantly enhanced durability under accelerated stability tests. The combination of the intrinsic activity and stability of single Co sites, along with unique catalyst architecture, provide new insight into designing efficient PGM-free electrodes with improved performance and durability.
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