Comprehensive Spectroscopic Elucidation of Atomically Dispersed FeN <sub>4</sub> Active Sites of Fe‐N‐C Electrocatalysts
ABSTRACT To gain insights into single‐atom active sites of iron, nitrogen‐doped carbon (Fe‐N‐C), we performed comprehensive element‐specific spectroscopies including Fe K ‐edge X‐ray absorption, 57 Fe Mössbauer, and Fe Kβ 1,3 and valence‐to‐core (VtC) X‐ray emission spectroscopy for two Fe‐N‐C electrocatalysts that exclusively have atomically dispersed FeN 4 active sites for the oxygen reduction reaction. Experimental VtC X‐ray emission spectra (VtC‐XES) coupled with spectral simulation of FeN 4 active site models allowed us to determine the dominant active site in each catalyst: FeN 4 active sites with 14‐membered or 16‐membered rings. Our study will open up possibilities to understand more details on active site structure–activity relationships not only for Fe‐N‐C electrocatalysts but also the other single‐atom (electro)catalysts.
Authors
- Ichizo Yagi (ORCID: https://orcid.org/0000-0002-4005-9440)
- Takaya Mitsui (ORCID: https://orcid.org/0000-0001-5502-9327)
- Hiroyuki Asakura (ORCID: https://orcid.org/0000-0001-6451-4738)
- Masaru Kato (ORCID: https://orcid.org/0000-0002-2845-3525)
- Shun Saito (ORCID: https://orcid.org/0000-0002-6163-2752)
- Akira Onoda (ORCID: https://orcid.org/0000-0002-5791-4386)
- Kosuke Fujiwara (ORCID: https://orcid.org/0000-0002-3772-0445)
- Kenji Ishii (ORCID: https://orcid.org/0000-0002-6465-8202)
- Koki Matsumoto (ORCID: https://orcid.org/0000-0002-4220-7304)
- Siqi Xie (ORCID: https://orcid.org/0000-0002-4797-5521)
Institutions
- Osaka Gakuin University (JP)
- Hokkaido University (JP)
- National Institutes for Quantum Science and Technology (JP)
- Kindai University (JP)
- The University of Osaka (JP)
Publication Details
- Journal
- Small Methods
- Published
- 2026-08-14
- DOI
- https://doi.org/10.1002/smtd.70946
- Primary Topic
- Electrocatalysts for Energy Conversion
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Ministry of Education, Culture, Sports, Science and Technology
- Hokkaido University
- Institute for Materials Research, Tohoku University
- Information Technology Center, Nagoya University
- Division of Materials Research