Atomically dispersed Fe–Nx active sites within hierarchical mesoporous carbon as efficient electrocatalysts for the oxygen reduction reaction

Abstract

It is still a great challenge to develop highly efficient catalysts with earth abundant materials to replace the precious platinum group metal (PGM) catalysts for the oxygen reduction reaction (ORR). Here, we report a self-sacrificing template strategy to synthesize hierarchical mesoporous carbon materials with atomically dispersed Fe–N_x active sites. Derived from an Fe–polydopamine precursor obtained via in situ polymerization of dopamine and etching of a cobalt template using an FeCl₃ solution, the resultant catalyst shows a high specific surface area (1229.3 m² g⁻¹), a hierarchical mesoporous structure, an improved hydrophilicity, and abundant atomically dispersed Fe–N_x active sites. As a result, the single atom catalyst exhibits a remarkable activity and durability in 0.1 M KOH with an onset and half-wave potential of 1.03 and 0.88 V, respectively, which surpass those of its commercial Pt/C counterpart. In acidic and neutral media, the catalyst also exhibits a comparable electrocatalytic activity to but much greater durability than commercial Pt/C. This work opens a new avenue for synthesis of cost-effective catalysts at the atomic scale for efficient energy conversion.