催化作用
铂金
电解质
碳纤维
化学工程
氢
燃料电池
氮气
氧气
化学
多孔性
膜
材料科学
无机化学
电极
有机化学
复合材料
工程类
物理化学
复合数
生物化学
作者
Hyun Kyu Chung,David A. Cullen,Drew Higgins,Brian T. Sneed,Edward F. Holby,Karren L. More,Piotr Zelenay
出处
期刊:Science
[American Association for the Advancement of Science (AAAS)]
日期:2017-08-04
卷期号:357 (6350): 479-484
被引量:1268
标识
DOI:10.1126/science.aan2255
摘要
Platinum group metal-free (PGM-free) metal-nitrogen-carbon catalysts have emerged as a promising alternative to their costly platinum (Pt)-based counterparts in polymer electrolyte fuel cells (PEFCs) but still face some major challenges, including (i) the identification of the most relevant catalytic site for the oxygen reduction reaction (ORR) and (ii) demonstration of competitive PEFC performance under automotive-application conditions in the hydrogen (H2)-air fuel cell. Herein, we demonstrate H2-air performance gains achieved with an iron-nitrogen-carbon catalyst synthesized with two nitrogen precursors that developed hierarchical porosity. Current densities recorded in the kinetic region of cathode operation, at fuel cell voltages greater than ~0.75 V, were the same as those obtained with a Pt cathode at a loading of 0.1 milligram of Pt per centimeter squared. The proposed catalytic active site, carbon-embedded nitrogen-coordinated iron (FeN4), was directly visualized with aberration-corrected scanning transmission electron microscopy, and the contributions of these active sites associated with specific lattice-level carbon structures were explored computationally.
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