气候变化领域集成服务门户(CCPortal): A specific demetalation of Fe-N4 catalytic sites in the micropores of NC-Ar + NH3 is at the origin of the initial activity loss of the highly active Fe/N/C catalyst used for the reduction of oxygen in PEM fuel cells

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DOI	10.1039/c7ee02302b
	A specific demetalation of Fe-N4 catalytic sites in the micropores of NC-Ar + NH3 is at the origin of the initial activity loss of the highly active Fe/N/C catalyst used for the reduction of oxygen in PEM fuel cells
	Chenitz R.; Kramm U.I.; Lefèvre M.; Glibin V.; Zhang G.; Sun S.; Dodelet J.-P.
发表日期	2018
ISSN	17545692
起始页码	365
结束页码	382
卷号	11 期号:2
英文摘要	In this study, we explored the behavior of NC-Ar + NH3, an initially highly active catalyst for oxygen electroreduction, in H2/air fuel cells from 0.8 to 0.2 V at 80 °C and 25 °C, in order to find the causes of its instability. We discovered that the decay of the current density always involves the superposition of fast and slow first order kinetics, for which half-lives were obtained. The half-life of the fast decay was practically the same at all potentials and temperatures with a value of around 138 ± 55 min, while the half-life of the slow decay greatly varied from a minimum of ≈2400 min (40 h) to infinity. From the adsorption-desorption isotherm of NC-Ar + NH3, it was deduced that the Fe/N/C carbonaceous catalyst is characterized by interconnected open-end slit-shaped micropores, in which water (with dissolved H+ and O2) quickly flows in the fuel cells if their width is ≥0.7 nm as it has no interaction with the hydrophobic walls of the micropores. The driving force of this quick water flow is the humidified air streaming through the working cathode. Fe-N4-like active sites are thermodynamically stable in stagnant acidic conditions, but according to the Le Chatelier principle, they demetalate in the flux of water running into the micropores. This specific demetalation is the cause of the initial loss of ORR activity of NC-Ar + NH3 catalysts assigned to the fast current decay in fuel cells. © 2018 The Royal Society of Chemistry.
英文关键词	Catalysts; Electrolytic reduction; Flow of water; Gas fuel purification; Hydrophobicity; Microporosity; Oxygen; Proton exchange membrane fuel cells (PEMFC); Acidic conditions; Adsorption desorption isotherms; Carbonaceous catalyst; First order kinetics; Le chatelier principle; Oxygen electro reductions; Reduction of oxygen; Thermodynamically stable; Iron compounds; adsorption; catalysis; catalyst; chemical reaction; desorption; electrochemical method; fuel cell; inorganic compound; isotherm; oxygen; reaction kinetics; reduction; thermodynamics; water flow
语种	英语
来源期刊	Energy & Environmental Science
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/190325
作者单位	INRS-Énergie, Matériaux et Télécommunications, 1650 Boulevard Lionel, Boulet Varennes, QC J3X 1S2, Canada; TU Darmstadt, Graduate School Energy Science and Engineering, Department of Materials- and Earth Sciences, Otto-Berndt-Str. 3, Darmstadt, 64287, Germany; Canetique Electrocatalysis, 1650 Boulevard Lionel, Boulet Varennes, QC J3X 1S2, Canada; Department of Chemical and Biochemical Engineering, University of Western Ontario, London, N6A 5B9, Canada
推荐引用方式 GB/T 7714	Chenitz R.,Kramm U.I.,Lefèvre M.,et al. A specific demetalation of Fe-N4 catalytic sites in the micropores of NC-Ar + NH3 is at the origin of the initial activity loss of the highly active Fe/N/C catalyst used for the reduction of oxygen in PEM fuel cells[J],2018,11(2).
APA	Chenitz R..,Kramm U.I..,Lefèvre M..,Glibin V..,Zhang G..,...&Dodelet J.-P..(2018).A specific demetalation of Fe-N4 catalytic sites in the micropores of NC-Ar + NH3 is at the origin of the initial activity loss of the highly active Fe/N/C catalyst used for the reduction of oxygen in PEM fuel cells.Energy & Environmental Science,11(2).
MLA	Chenitz R.,et al."A specific demetalation of Fe-N4 catalytic sites in the micropores of NC-Ar + NH3 is at the origin of the initial activity loss of the highly active Fe/N/C catalyst used for the reduction of oxygen in PEM fuel cells".Energy & Environmental Science 11.2(2018).