Fe–N-doped hierarchical mesoporous carbon nanomaterials as efficient catalysts for oxygen reduction in both acidic and alkaline media

Abstract

Fe-based electrocatalysts are known as one of the best alternatives to replace platinum in polymer electrolyte membrane fuel cells (PEMFCs) for their future application in small portable or automotive power sources. However, one key obstacle for the application of Fe-based catalysts is their dissatisfactory activity toward the oxygen reduction reaction (ORR). Herein, we demonstrate that agglomerated Fe₂O₃ nanoparticles are capable of improving the performance of Fe-based catalysts. The impact of the shape, size, and microstructure of Fe₂O₃ nanoparticles on the ORR activity of Fe-based catalysts is well discussed. All the results indicate that the Fe₂O₃ nanoparticles bound by high-index (110) facets may involve in the formation of numerous active sites for the ORR. The best Fe-based catalyst in this study exhibited superior ORR catalytic activity with its half-wave potential (E_1/2) only negatively shifting by 32 mV compared to that of commercial Pt/C in 0.1 M HClO₄ solution. Based on this catalyst, the peak power density of an air-breathing PEMFC reached approximately 63% of that of Pt/C (91 mW cm⁻²) in an air-conditioned room with a temperature of 20 °C.