气候变化领域集成服务门户(CCPortal): High-performance fuel cell cathodes exclusively containing atomically dispersed iron active sites

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DOI	10.1039/c9ee00877b
	High-performance fuel cell cathodes exclusively containing atomically dispersed iron active sites
	Zhang H.; Chung H.T.; Cullen D.A.; Wagner S.; Kramm U.I.; More K.L.; Zelenay P.; Wu G.
发表日期	2019
ISSN	1754-5692
起始页码	2548
结束页码	2558
卷号	12 期号:8
英文摘要	Platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) with atomically dispersed FeN4 sites have emerged as a potential replacement for low-PGM catalysts in acidic polymer electrolyte fuel cells (PEFCs). In this work, we carefully tuned the doped Fe content in zeolitic imidazolate framework (ZIF)-8 precursors and achieved complete atomic dispersion of FeN4 sites, the sole Fe species in the catalyst based on Mößbauer spectroscopy data. The Fe-N-C catalyst with the highest density of active sites achieved respectable ORR activity in rotating disk electrode (RDE) testing with a half-wave potential (E1/2) of 0.88 ± 0.01 V vs. the reversible hydrogen electrode (RHE) in 0.5 M H2SO4 electrolyte. The activity degradation was found to be more significant when holding the potential at 0.85 V relative to standard potential cycling (0.6-1.0 V) in O2 saturated acid electrolyte. The post-mortem electron microscopy analysis provides insights into possible catalyst degradation mechanisms associated with Fe-N coordination cleavage and carbon corrosion. High ORR activity was confirmed in fuel cell testing, which also divulged the promising performance of the catalysts at practical PEFC voltages. We conclude that the key factor behind the high ORR activity of the Fe-N-C catalyst is the optimum Fe content in the ZIF-8 precursor. While too little Fe in the precursors results in an insufficient density of FeN4 sites, too much Fe leads to the formation of clusters and an ensuing significant loss in catalytic activity due to the loss of atomically dispersed Fe to inactive clusters or even nanoparticles. Advanced electron microscopy was used to obtain insights into the clustering of Fe atoms as a function of the doped Fe content. The Fe content in the precursor also affects other key catalyst properties such as the particle size, porosity, nitrogen-doping level, and carbon microstructure. Thanks to using model catalysts exclusively containing FeN4 sites, it was possible to directly correlate the ORR activity with the density of FeN4 species in the catalyst. © The Royal Society of Chemistry 2019.
语种	英语
scopus关键词	Carbon; Corrosion; Degradation; Electrodes; Electrolytic reduction; Electron microscopes; Electron microscopy; Iron; Particle size; Particle size analysis; Polyelectrolytes; Proton exchange membrane fuel cells (PEMFC); Rotating disks; Solid electrolytes; Carbon microstructures; Electron microscopy analysis; High performance fuel cells; Oxygen reduction reaction; Platinum group metals; Reversible hydrogen electrodes; Rotating disk electrodes; Zeolitic imidazolate frameworks; Catalyst activity; catalyst; electrode; electrolyte; fuel cell; iron; performance assessment; reduction
来源期刊	Energy and Environmental Science
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/162916
作者单位	Department of Chemical and Biological Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260, United States; Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, United States; Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Technische Universität Darmstadt, Department of Materials- and Earth Sciences, Darmstadt, 64287, Germany; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
推荐引用方式 GB/T 7714	Zhang H.,Chung H.T.,Cullen D.A.,et al. High-performance fuel cell cathodes exclusively containing atomically dispersed iron active sites[J],2019,12(8).
APA	Zhang H..,Chung H.T..,Cullen D.A..,Wagner S..,Kramm U.I..,...&Wu G..(2019).High-performance fuel cell cathodes exclusively containing atomically dispersed iron active sites.Energy and Environmental Science,12(8).
MLA	Zhang H.,et al."High-performance fuel cell cathodes exclusively containing atomically dispersed iron active sites".Energy and Environmental Science 12.8(2019).