Fe–N-Doped carbon foam nanosheets with embedded Fe2O3 nanoparticles for highly efficient oxygen reduction in both alkaline and acidic media

Abstract

We report a facile two-step pyrolysis and acid leaching process to fabricate a high performance oxygen reduction reaction (ORR) electrocatalyst Fe₂O₃@Fe–N–C, which is composed of Fe–N-doped carbon foam nanosheets with embedded carbon coated Fe₂O₃ nanoparticles to enhance the ORR performance in acidic medium. The ORR activities of the Fe₂O₃@Fe–N–C electrocatalysts obtained at different pyrolysis temperatures are investigated and the catalyst fabricated by pyrolysis at 800 °C displays the optimal activity. A rotating disk electrode (RDE) study reveals that it exhibits a positive half-wave potential of 0.535 V (vs. Ag/AgCl), high selectivity (4e⁻ process), excellent long-term stability (96.3% of the initial current remaining after 20 000 s of continuous operation) and good tolerance against the methanol-crossover effect in acidic medium, making it a promising candidate for substituting the commercial Pt/C catalyst in polymer electrolyte membrane fuel cells (PEMFCs). The remarkable ORR activity originates from the cooperative effect of carbon coated Fe₂O₃ nanocrystals and Fe–N-doped carbon foam nanosheets. Moreover, the porous structure, high specific surface area, and electron conductivity could contribute to the enhanced ORR performance.