Unravelling the Stability Stressors of Atomically Dispersed Fe–N–C Oxygen Reduction Catalysts

Xiaohong Xie; Boyang Li; Pan Xu; Moulay Tahar Sougrati; Ricardo Garcia-Serres; David A. Cullen; A. Jeremy Kropf; Fan Xia; Miao Song; Sulay Saha; Yachao Zeng; Mark H. Engelhard; Mark E. Bowden; Hanguang Zhang; Litao Yan; Teresa Lemmon; Xiaohong S. Li; Ulises Martinez; Yingwen Cheng; Gang Wu; Piotr Zelenay; Vijay Ramani; Deborah J. Myers; Frédéric Jaouen; Lijun Yang; Guofeng Wang; Yuyan Shao

doi:10.1021/jacs.5c15451

Unravelling the Stability Stressors of Atomically Dispersed Fe–N–C Oxygen Reduction Catalysts

Xiaohong Xie
, Boyang Li
, Pan Xu
, Moulay Tahar Sougrati
, Ricardo Garcia-Serres
, David A. Cullen
, A. Jeremy Kropf
, Fan Xia
, Miao Song
, Sulay Saha
, Yachao Zeng
, Mark H. Engelhard
, Mark E. Bowden
, Hanguang Zhang
, Litao Yan
, Teresa Lemmon
, Xiaohong S. Li
, Ulises Martinez
, Yingwen Cheng
, Gang Wu

Piotr Zelenay, Vijay Ramani, Deborah J. Myers, Frédéric Jaouen, Lijun Yang, Guofeng Wang, Yuyan Shao

electron Microscopy and Microanalysis

Research output: Contribution to journal › Article › peer-review

14 Scopus citations

Abstract

Enhancing the catalytic stability of Fe–N–C catalysts for cathodic oxygen reduction in proton-exchange membrane fuel cells (PEMFCs) necessitates an in-depth understanding of their degradation mechanisms. This study identifies key stressors affecting the stability of Fe–N–C catalysts, specifically acidic environment, oxygen (O₂), and reactive oxygen species (ROS). Through ex situ/operando experiments, we show that the oxidation of local carbon by acidic environment + O₂ + ROS, along with the demetalation of catalytic FeN_xC_y sites by O₂ or O₂ + ROS, is the primary factor responsible for the initial fast degradation of Fe–N–C catalysts. The demetalation of FeN_xC_y sites, influenced by O₂, in particular by O₂ + ROS, leads to the subsequent gradual degradation of Fe–N–C. Notably, FeN₄C₁₂-type active sites are more susceptible to demetalation than FeN₄C₁₀-type sites in O₂ or O₂ + ROS. Our findings indicate that, besides constructing more stable FeN_xC_y sites, preventing local carbon oxidation and scavenging of ROS are all critical for maintaining the stability of Fe–N–C catalysts.

Original language	English
Pages (from-to)	48117-48126
Number of pages	10
Journal	Journal of the American Chemical Society
Volume	147
Issue number	52
DOIs	https://doi.org/10.1021/jacs.5c15451
State	Published - Dec 31 2025

Funding

The authors acknowledge support from the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through the Electrocatalysis consortium (ElectroCat) and the DOE program managers, Gregory Kleen, David Peterson, Simon Thompson, and Dimitrios Papageorgopoulos. The XPS measurement was conducted at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility at Pacific Northwest National Laboratory (PNNL), which is sponsored by DOE’s Office of Biological and Environmental Research (BER). PNNL is operated by Battelle for the U.S. DOE under Contract DE-AC05-76RLO1830. X-ray spectroscopy analysis was carried out at MRCAT at the Advanced Photon Source (APS), an Office of Science user facility operated for the DOE’s Office of Science by Argonne National Laboratory (ANL) under Contract DE-AC02-06CH11357. The operation of MRCAT is supported by both DOE and the MRCAT member institutions. ANL is operated for the US DOE by UChicago Argonne LLC under Contract DE-AC02-06CH11357. Electron microscopy research of material was conducted as a part of a user project at the Center for Nanophase Materials Sciences (CNMS), a DOE’s Office of Science user facility at Oak Ridge National Laboratory. The spin-polarized DFT calculations were performed on the computers of the University of Pittsburgh Center for Research Computing (CRC) as well as the Extreme Science and Engineering Discovery Environment (XSEDE), which is funded by the National Science Foundation (NSF) grant number ACI-1053575. Cryogenic Mössbauer characterization received funding from the French National Research Agency (Labex ARCANE, CBH-EUR-GS, ANR-17-EURE-0003).

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Xie, X., Li, B., Xu, P., Sougrati, M. T., Garcia-Serres, R., Cullen, D. A., Kropf, A. J., Xia, F., Song, M., Saha, S., Zeng, Y., Engelhard, M. H., Bowden, M. E., Zhang, H., Yan, L., Lemmon, T., Li, X. S., Martinez, U., Cheng, Y., ... Shao, Y. (2025). Unravelling the Stability Stressors of Atomically Dispersed Fe–N–C Oxygen Reduction Catalysts. Journal of the American Chemical Society, 147(52), 48117-48126. https://doi.org/10.1021/jacs.5c15451

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title = "Unravelling the Stability Stressors of Atomically Dispersed Fe{\textendash}N{\textendash}C Oxygen Reduction Catalysts",

abstract = "Enhancing the catalytic stability of Fe{\textendash}N{\textendash}C catalysts for cathodic oxygen reduction in proton-exchange membrane fuel cells (PEMFCs) necessitates an in-depth understanding of their degradation mechanisms. This study identifies key stressors affecting the stability of Fe{\textendash}N{\textendash}C catalysts, specifically acidic environment, oxygen (O2), and reactive oxygen species (ROS). Through ex situ/operando experiments, we show that the oxidation of local carbon by acidic environment + O2 + ROS, along with the demetalation of catalytic FeNxCy sites by O2 or O2 + ROS, is the primary factor responsible for the initial fast degradation of Fe{\textendash}N{\textendash}C catalysts. The demetalation of FeNxCy sites, influenced by O2, in particular by O2 + ROS, leads to the subsequent gradual degradation of Fe{\textendash}N{\textendash}C. Notably, FeN4C12-type active sites are more susceptible to demetalation than FeN4C10-type sites in O2 or O2 + ROS. Our findings indicate that, besides constructing more stable FeNxCy sites, preventing local carbon oxidation and scavenging of ROS are all critical for maintaining the stability of Fe{\textendash}N{\textendash}C catalysts.",

author = "Xiaohong Xie and Boyang Li and Pan Xu and Sougrati, \{Moulay Tahar\} and Ricardo Garcia-Serres and Cullen, \{David A.\} and Kropf, \{A. Jeremy\} and Fan Xia and Miao Song and Sulay Saha and Yachao Zeng and Engelhard, \{Mark H.\} and Bowden, \{Mark E.\} and Hanguang Zhang and Litao Yan and Teresa Lemmon and Li, \{Xiaohong S.\} and Ulises Martinez and Yingwen Cheng and Gang Wu and Piotr Zelenay and Vijay Ramani and Myers, \{Deborah J.\} and Fr{\'e}d{\'e}ric Jaouen and Lijun Yang and Guofeng Wang and Yuyan Shao",

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year = "2025",

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day = "31",

doi = "10.1021/jacs.5c15451",

language = "English",

volume = "147",

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Xie, X, Li, B, Xu, P, Sougrati, MT, Garcia-Serres, R, Cullen, DA, Kropf, AJ, Xia, F, Song, M, Saha, S, Zeng, Y, Engelhard, MH, Bowden, ME, Zhang, H, Yan, L, Lemmon, T, Li, XS, Martinez, U, Cheng, Y, Wu, G, Zelenay, P, Ramani, V, Myers, DJ, Jaouen, F, Yang, L, Wang, G & Shao, Y 2025, 'Unravelling the Stability Stressors of Atomically Dispersed Fe–N–C Oxygen Reduction Catalysts', Journal of the American Chemical Society, vol. 147, no. 52, pp. 48117-48126. https://doi.org/10.1021/jacs.5c15451

TY - JOUR

T1 - Unravelling the Stability Stressors of Atomically Dispersed Fe–N–C Oxygen Reduction Catalysts

AU - Xie, Xiaohong

AU - Li, Boyang

AU - Xu, Pan

AU - Sougrati, Moulay Tahar

AU - Garcia-Serres, Ricardo

AU - Cullen, David A.

AU - Kropf, A. Jeremy

AU - Xia, Fan

AU - Song, Miao

AU - Saha, Sulay

AU - Zeng, Yachao

AU - Engelhard, Mark H.

AU - Bowden, Mark E.

AU - Zhang, Hanguang

AU - Yan, Litao

AU - Lemmon, Teresa

AU - Li, Xiaohong S.

AU - Martinez, Ulises

AU - Cheng, Yingwen

AU - Wu, Gang

AU - Zelenay, Piotr

AU - Ramani, Vijay

AU - Myers, Deborah J.

AU - Jaouen, Frédéric

AU - Yang, Lijun

AU - Wang, Guofeng

AU - Shao, Yuyan

PY - 2025/12/31

Y1 - 2025/12/31

N2 - Enhancing the catalytic stability of Fe–N–C catalysts for cathodic oxygen reduction in proton-exchange membrane fuel cells (PEMFCs) necessitates an in-depth understanding of their degradation mechanisms. This study identifies key stressors affecting the stability of Fe–N–C catalysts, specifically acidic environment, oxygen (O2), and reactive oxygen species (ROS). Through ex situ/operando experiments, we show that the oxidation of local carbon by acidic environment + O2 + ROS, along with the demetalation of catalytic FeNxCy sites by O2 or O2 + ROS, is the primary factor responsible for the initial fast degradation of Fe–N–C catalysts. The demetalation of FeNxCy sites, influenced by O2, in particular by O2 + ROS, leads to the subsequent gradual degradation of Fe–N–C. Notably, FeN4C12-type active sites are more susceptible to demetalation than FeN4C10-type sites in O2 or O2 + ROS. Our findings indicate that, besides constructing more stable FeNxCy sites, preventing local carbon oxidation and scavenging of ROS are all critical for maintaining the stability of Fe–N–C catalysts.

AB - Enhancing the catalytic stability of Fe–N–C catalysts for cathodic oxygen reduction in proton-exchange membrane fuel cells (PEMFCs) necessitates an in-depth understanding of their degradation mechanisms. This study identifies key stressors affecting the stability of Fe–N–C catalysts, specifically acidic environment, oxygen (O2), and reactive oxygen species (ROS). Through ex situ/operando experiments, we show that the oxidation of local carbon by acidic environment + O2 + ROS, along with the demetalation of catalytic FeNxCy sites by O2 or O2 + ROS, is the primary factor responsible for the initial fast degradation of Fe–N–C catalysts. The demetalation of FeNxCy sites, influenced by O2, in particular by O2 + ROS, leads to the subsequent gradual degradation of Fe–N–C. Notably, FeN4C12-type active sites are more susceptible to demetalation than FeN4C10-type sites in O2 or O2 + ROS. Our findings indicate that, besides constructing more stable FeNxCy sites, preventing local carbon oxidation and scavenging of ROS are all critical for maintaining the stability of Fe–N–C catalysts.

UR - https://www.scopus.com/pages/publications/105026454059

U2 - 10.1021/jacs.5c15451

DO - 10.1021/jacs.5c15451

M3 - Article

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AN - SCOPUS:105026454059

SN - 0002-7863

VL - 147

SP - 48117

EP - 48126

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 52

ER -

Unravelling the Stability Stressors of Atomically Dispersed Fe–N–C Oxygen Reduction Catalysts

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