Electron Transfer from Encapsulated Fe3C to the Outermost N‐Doped Carbon Layer for Superior ORR

• Published in: Advanced functional materials 2024-10, Vol.34 (40), p.n/a
• Main Authors: Quílez‐Bermejo, Javier, Daouli, Ayoub, Dalí, Sergio García, Cui, Yingdan, Zitolo, Andrea, Castro‐Gutiérrez, Jimena, Emo, Mélanie, Izquierdo, Maria T., Mustain, William, Badawi, Michael, Celzard, Alain, Fierro, Vanessa
• Format: Article
• Language: English
• Subjects: Anion exchanging; C1N1; Carbon; Catalytic activity; Cementite; Chemical reduction; Chemical synthesis; Electron transfer; Encapsulation; encapsulation in N‐doped carbon; Fe3C; Fuel cells; Iron carbides; oxygen reduction reaction (ORR); Oxygen reduction reactions
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202403810

Encapsulating Fe3C in carbon layers has emerged as an innovative strategy for protecting Fe3C while preserving its high oxygen reduction activity. However, fundamental questions persist regarding the active sites of encapsulated Fe3C due to the restricted accessibility of oxygen molecules to the metal sites. Herein, the intrinsic electron transfer mechanisms of Fe3C nanoparticles encapsulated in N‐doped carbon materials are unveiled for oxygen reduction electrocatalysis. The precision‐structured C1N1 material is used to synthesize N‐doped carbons with encapsulated Fe3C, significantly enhancing catalytic activity (EONSET = 0.98 V) and achieving near‐100% operational stability. In anion‐exchange membrane fuel cells, an excellent peak power density of 830 mW cm−2 is reached at 60 °C. The experimental and computational results revealed that the presence of Fe3C cores dynamically triggers electron transfer to the outermost carbon layer. This phenomenon amplifies the oxygen reduction reaction performance at N sites, contributing significantly to the observed catalytic enhancement. N‐doped carbon with encapsulated Fe3C nanoparticles within carbon layers shows high oxygen reduction activity and state‐of‐the‐art performance in fuel cell experiments. Encapsulation preserves the catalytic activity, and DFT simulations unveil electron transfer mechanisms from Fe3C cores to N active sites located in the outermost N‐doped carbon layer, boosting the electrocatalytic activity.