Contribution of Mg-templated porosity to activity and durability in Fe-N-C O₂ reduction catalysts
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Atomically dispersed Fe in N-doped carbon (Fe–N–C) catalysts are leading platinum-group-metal-free candidates for the O2 reduction reaction in proton exchange membrane fuel cells (PEMFCs). Zeolitic imidazolate framework (ZIF-8) derived Fe–N–C present the most promising performance; however, they possess a narrow distribution of small micropores, which limits active site accessibility. Here, to induce hierarchical porosity in Fe–N–C, we report a systematic study on MgCl2·6H2O-templated ZIF-8-derived Fe–N–C catalysts for the O2 reduction reaction. MgCl2·6H2O addition induced complete Zn removal, collapse of the ZIF-8 framework, and formation of large micro- and mesopores, with graphene-like structures. N content was markedly reduced, with conversion from pyridinic to pyrrolic N species. Rotating disc electrode tests showed a progressive increase in O2 reduction activity with MgCl2·6H2O, which is strongly correlated (R2 = 0.98) to the formation of large micropores and small mesopores (1–4 nm). This introduces an indirect structure–activity design principle for Fe–N–Cs. The enhanced Fe–N–C porosity also leads to increased degradation rates under accelerated stress test conditions, which we attributed to the oxidation of disordered carbon domains and active Fe loss. This study highlights a key trade-off between porosity-driven O2 reduction activity and durability in Fe–N–C catalysts.
Date Issued
2026-03-16
2026-04-14
Date Acceptance
2026-02-24
Citation
Materials Advances, 2026, 2026 (7), pp.3524-3531
ISSN
2633-5409
Publisher
The Royal Society of Chemistry
Start Page
3524
End Page
3531
Journal / Book Title
Materials Advances
Volume
2026
Issue
7
Copyright Statement
© 2026 The Author(s). Published by the Royal Society of Chemistry. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
License URL
Identifier
10.1039/d5ma01488c
Publication Status
Published
Date Publish Online
2026-03-16