首页|Fe-N-C core-shell catalysts with single low-spin Fe(Ⅱ)-N4 species for oxygen reduction reaction and high-performance proton exchange membrane fuel cells

Fe-N-C core-shell catalysts with single low-spin Fe(Ⅱ)-N4 species for oxygen reduction reaction and high-performance proton exchange membrane fuel cells

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Fe-N-doped carbon materials(Fe-N-C)are promising candidates for oxygen reduction reaction(ORR)rel-ative to Pt-based catalysts in proton exchange membrane fuel cells(PEMFCs).However,the intrinsic con-tributions of Fe-N4 moiety with different chemical/spin states(e.g.D1,D2,D3)to ORR are unclear since various states coexist inevitably.In the present work,Fe-N-C core-shell nanocatalyst with single low-spin Fe(Ⅱ)-N4 species(D1)is synthesized and identified with ex-situ ultralow temperature Mössbauer spectroscopy(T=1.6 K)that could essentially differentiate various Fe-N4 states and invisible Fe-O spe-cies.By quantifying with CO-pulse chemisorption,site density and turnover frequency of Fe-N-C catalysts reach 2.4 × 1019 site g-1 and 23 e site-1 s-1 during the ORR,respectively.Half-wave potential(0.915 VRHE)of the Fe-N-C catalyst is more positive(approximately 54 mV)than that of Pt/C.Moreover,we observe that the performance of PEMFCs on Fe-N-C almost achieves the 2025 target of the US Department of Energy by demonstrating a current density of 1.037 A cm-2 combined with the peak power density of 0.685 W cm-2,suggesting the critical role of Fe(Ⅱ)-N4 site(D1).After 500 h of running,PEMFCs still deliver a power density of 1.26 W cm-2 at 1.0 bar H2-O2.An unexpected rate-determining step is figured out by isotopic labelling experiment and theoretical calculation.This work not only offers valuable insights regarding the intrinsic contribution of Fe-N4 with a single spin state to alkaline/acidic ORR,but also provides great opportunities for developing high-performance stable PEMFCs.

Fuel cellsOxygen reduction reactionNon-platinum group metals(PGMs)Isotopic labellingActive siteTOF

Yan Wan、Linhui Yu、Bingxin Yang、Caihong Li、Chen Fang、Wei Guo、Fang-Xing Xiao、Yangming Lin

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Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials,Xiamen Institute of Rare Earth Materials,Haixi Institute,Chinese Academy of Sciences,Xiamen 361021,Fujian,China

Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences,Fuzhou 350002,Fujian,China

CAS Key Laboratory of Urban Pollutant Conversion,Institute of Urban Environment,Chinese Academy of Sciences,Xiamen 361021,Fujian,China

College of Chemistry and Materials Science,Fujian Normal University,Fuzhou 350117,Fujian,China

College of Materials Science and Engineering,Fuzhou University,New Campus,Minhou 350108,Fujian,China

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the"Hundred Talents Program"of the Chinese Academy of Sciencesthe"Young Talents Training Program"of the Shanghai Branch of the Chinese Academy of SciencesXiamen City Natural Science Foundation of ChinaXiamen City Natural Science Foundation of ChinaNational Science Youth Foundation of ChinaFujian Provincial Natural Science Foundation of ChinaOpen Source Foundation of State Key Laboratory of Structural Chemistry

3502Z202270853502Z20227256222022052022J01502

2024

10.1016/j.jechem.2024.01.074

能源化学
中国科学院大连化学物理研究所 中国科学院成都有机化学研究所

能源化学

CSTPCDEI
影响因子：0.654
ISSN：2095-4956
年,卷(期)：2024.93(6)
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