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Understanding the Activity Trade-Off between Tetrapyrrolic Fe-NCs and Co-NCs in the Alkaline Oxygen Reduction Reaction

  • A water-free ionothermal synthesis of porous magnesium-imprinted nitrogen-doped carbon (Mg–NC) materials is introduced to prepare a platform material to investigate electrocatalytic structure-performance relations. Atomically dispersed Co- and Fe-NCs isomorphic to the pristine Mg-NCs are prepared by ion-exchange reactions. The current Mg-templating strategy enables relatively high pyrolysis product yields of up to 50 wt% and resultant Fe-NC and Co-NC catalysts contain high and comparable active metal loading of up to 2.52 wt% Fe and 2.29 wt% Co, respectively. A combination of X-ray spectroscopies with DFT studies reveals a tetrapyrrolic structure of the coordination sites, originating from a pyrolytic magnesium template ion reaction within the ionothermal synthesis. Two sets of highly active isomorphic tetrapyrrolic Fe-NCs and Co-NCs are utilized to understand the differences in intrinsic electrocatalytic performance of Co-NCs and Fe-NCs towards the alkaline oxygen reduction reactionA water-free ionothermal synthesis of porous magnesium-imprinted nitrogen-doped carbon (Mg–NC) materials is introduced to prepare a platform material to investigate electrocatalytic structure-performance relations. Atomically dispersed Co- and Fe-NCs isomorphic to the pristine Mg-NCs are prepared by ion-exchange reactions. The current Mg-templating strategy enables relatively high pyrolysis product yields of up to 50 wt% and resultant Fe-NC and Co-NC catalysts contain high and comparable active metal loading of up to 2.52 wt% Fe and 2.29 wt% Co, respectively. A combination of X-ray spectroscopies with DFT studies reveals a tetrapyrrolic structure of the coordination sites, originating from a pyrolytic magnesium template ion reaction within the ionothermal synthesis. Two sets of highly active isomorphic tetrapyrrolic Fe-NCs and Co-NCs are utilized to understand the differences in intrinsic electrocatalytic performance of Co-NCs and Fe-NCs towards the alkaline oxygen reduction reaction (ORR). Despite their superior valence electronic properties to facilitate the initial outer-sphere electron transfer to O2, Co-NCs show significantly lower performance than Fe-NC with comparable loading. Although the generally discussed weaker binding of peroxide intermediates to CoN4 sites compared to FeN4 sites is evident, experimental and theoretical investigation reveal that it is the underlying peroxide oxidation activity that suppresses the oxygen reduction activity of M-NCs. The high peroxide oxidation activity of Co-NCs explains their reduced alkaline ORR relative to Fe-NCs, shedding light on the understated significance of controlling peroxide chemistry for the optimizing cathodic performance.zeige mehrzeige weniger

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Autor*innen:Arielle Rieck, Jian Liang LowORCiD, Simon Dietzmann, Jörg RadnikORCiD, Zahra Teimouri, Drew Higgins, Vasile-Dan HodoroabaORCiD, Asad Mehmood, Tim-Patrick FellingerORCiD
Dokumenttyp:Preprint
Veröffentlichungsform:Graue Literatur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Understanding the Activity Trade-Off between Tetrapyrrolic Fe-NCs and Co-NCs in the Alkaline Oxygen Reduction Reaction
Jahr der Erstveröffentlichung:2025
Organisationseinheit der BAM:3 Gefahrgutumschließungen; Energiespeicher
3 Gefahrgutumschließungen; Energiespeicher / 3.6 Elektrochemische Energiematerialien
6 Materialchemie
6 Materialchemie / 6.1 Oberflächen- und Dünnschichtanalyse
Veröffentlichende Institution:Bundesanstalt für Materialforschung und -prüfung (BAM)
Erste Seite:1
Letzte Seite:24
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Angewandte Physik
Freie Schlagwörter:Magnesium Imprinting; Metal- and nitrogen-doped carbon (M-N-C); Nitrogen doped Carbon; Oxygen Reduction Reaction (ORR); Tetrapyrrolic Sites
Themenfelder/Aktivitätsfelder der BAM:Energie
Energie / Elektrische Energiespeicher und -umwandlung
DOI:10.26434/chemrxiv-2025-s59s5
URN:urn:nbn:de:kobv:b43-651487
Verfügbarkeit des Dokuments:Datei für die Öffentlichkeit verfügbar ("Open Access")
Lizenz (Deutsch):License LogoCreative Commons - CC BY - Namensnennung 4.0 International
Datum der Freischaltung:17.12.2025
Referierte Publikation:Nein
Schriftenreihen ohne Nummerierung:Preprints der BAM
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