Self-Supported Fe–N–C Electrocatalyst via Pyrolysis of EDTAFeNa Adsorbed on SBA-15 for the Oxygen Reduction Reaction

Self-supported Fe–N–C materials, without a carbon support and iron salt, were prepared via pyrolysis of a sole sodium ferric EDTA (EDTAFeNa) precursor containing C, N, and Fe atoms infused into hard template SBA-15, followed by base and acid etching and final heat treatment. The resultant EDTAFeNa-AL-HT2(SBA-15) demonstrated a four-electron pathway for the oxygen reduction reaction (ORR) in 0.1 M KOH with onset (Eonset) and half-wave (E1/2) potentials of 0.96 and 0.83 V versus RHE, respectively, closely matching those of benchmark Pt/C catalysts. The joint utilization of SBA-15 and etching endowed the self-supported Fe–N–C catalyst with high graphitization, moderate nitrogen doping, large surface area, hierarchical mesopores, and noncrystalline active Fe species with increased exposure over abundant pores, which synergistically enhanced ORR catalysis, giving rise to remarkable activity and selectivity while excluding contributions of crystalline Fe entities.