Modification of Conductive Carbon with N‐Coordinated Fe−Co Dual‐Metal Sites for Oxygen Reduction Reaction

Abstract

Abstract Earth‐abundant commercial conductive carbon materials are ideal electrocatalyst supports but cannot be directly utilized for single‐atom catalysts owing to the lack of anchoring sites. Therefore, we employed crosslink polymerization to modify the conductive carbon surface with Fe−Co dual‐site electrocatalysts for oxygen reduction reaction (ORR). First, metal‐coordinated polyurea (PU) aerogels were prepared using via crosslinked polymerization at ambient temperature. Then, carbon‐supported, atomically dispersed Fe−Co dual‐atom sites (FeCoNC/BP) were formed by high‐temperatures pyrolysis with a nitrogen source. FTIR and 13C NMR measurements showed PU linkages, while 15N NMR revealed metal–nitrogen coordination in the PU gels. Asymmetric, N‐coordinated, and isolated Fe−Co active structures were found after pyrolysis using XAS and STEM. In alkaline media, FeCoNC/BP exhibited excellent ORR activity, with a E1/2 of 0.93 V vs. RHE, higher than that of Pt/C (20 %) (0.90 V), FeNC/BP (0.88 V), and CoNC/BP (0.85 V). An accelerated durability test (ADT) on FeCoNC/BP indicated good durability over 35000 cycles. FeCoNC/BP also showed moderate ORR and ADT performance in acidic media. The macro/mesoporous N‐doped carbon structures enhanced the mass transport properties of the dual Fe−Co active‐sites. Therefore, modifying carbon supports with nonprecious metal catalysts may be a cost‐effective‐strategy for sustained electrochemical energy conversion.

Keywords

• conductive carbon
• oxygen reduction
• electrocatalysis
• dual metal-atom catalysts
• polyurea aerogels