- By:
- Xie, Xiaohong; Li, Boyang; Sougrati, Moulay; Cullen, David A; Kropf, A. Jeremy; Song, Miao; Saha, Sulay; Zeng, Yachao; Engelhard, Mark; Bowden, Mark; Zhang, Hanguang; Lemmon, Teresa; Liu, Xiaohong; Martinez, Ulises; Cheng, Yingwen; Wu, Gang; Zelenay, Piotr; Ramani, Vijay; Myers, Deborah; Jaouen, Frederic; yang, lijun; Wang, Guofeng; Shao, Yuyan
- Journal Name:
- Journal of the American Chemical Society
- Page Number:
- 48117-48126
- Volume:
- 147
- Issue Number:
- 52
- Publication Date:
- February 26, 2026
- View DOI Listing:
- https://doi.org/10.1021/jacs.5c15451
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 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.
