Article Highly active and stable Fe-N4 catalyst from unused natural resources for oxygen reduction reaction in acidic to alkaline medium

Edwin Osebe Nyangau ; Hiroya Abe ; Kazutoshi Haga ; Chie Ooka ; Kenji Hayashida ; Naoka Nagamura SAMURAI ORCID (National Institute for Materials Science) ; Kotaro Takeyasu ; Masaru Watanabe ; Yuta Nakayasu

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Edwin Osebe Nyangau, Hiroya Abe, Kazutoshi Haga, Chie Ooka, Kenji Hayashida, Naoka Nagamura, Kotaro Takeyasu, Masaru Watanabe, Yuta Nakayasu. Highly active and stable Fe-N4 catalyst from unused natural resources for oxygen reduction reaction in acidic to alkaline medium. Journal of Power Sources. 2025, 653 (), 237784. https://doi.org/10.1016/j.jpowsour.2025.237784

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(abstract)

Iron–nitrogen–carbon (Fe–N–C) catalysts with Fe–N4 coordination are promising alternatives to platinum-based materials for the oxygen reduction reaction (ORR), yet their instability in acidic media limits practical applications. Herein, we report a sustainable Fe–N–C catalyst (RH-Fe-N) synthesized from rice husks and pyrite, serving as carbon and iron sources, respectively. This approach eliminates the need for complex precursors such as metal–organic frameworks, using a simple three-step carbonization method including hydrothermal carbonization. The resulting catalyst incorporates Fe atoms into a carbon matrix with self-doped amorphous SiO2 from rice husks. Spectroscopic and theoretical analysis reveals a unique fifth Fe–O coordination within the SiO2 matrix, enhancing site stability and ORR activity. The catalyst also demonstrates superior durability, with 17 % and 16 % higher stability than Pt/C in acidic and neutral conditions, respectively. This work provides a low-cost, scalable, and eco-friendly strategy for developing high-performance ORR catalysts across all pH ranges, contributing to sustainable energy generation and circular economy goals.

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Keyword: Fe-N4, Oxygen reduction reaction, Catalyst stability, Universal pH, Iron-nitrogen-carbon catalyst

Date published: 2025-07-01

Publisher: Elsevier BV

Journal:

  • Journal of Power Sources (ISSN: 03787753) vol. 653 237784

Funding:

  • Ministry of the Environment, Government of Japan
  • Environmental Restoration and Conservation Agency
  • Ministry of Education, Culture, Sports, Science and Technology
  • Japan Society for the Promotion of Science 22K14533
  • Tohoku University

Manuscript type: Publisher's version (Version of record)

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First published URL: https://doi.org/10.1016/j.jpowsour.2025.237784

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Updated at: 2026-01-20 09:46:32 +0900

Published on MDR: 2026-01-20 12:23:00 +0900

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