Well-dispersed iron nanoparticles exposed within nitrogen-doped mesoporous carbon nanofibers by hydrogen-activation for oxygen-reduction reaction

Well-dispersed Fe nanoparticles exposed within N-doped mesoporous carbon nanofibers (Fe-NMCNF) are synthesized using electrospinning and H₂-activation. Their morphologies, crystal structures, chemical bonding states, and electrochemical performance are demonstrated at three calcination temperatures (700, 800, and 900 °C) during H₂-activation. Fe-NMCNF calcined at 800 °C had a high specific surface area of 467.6 m² g^-1, total pore volume of 0.88 cm³ g^-1, large average pore size of 7.5 nm, and large mesopore volume fraction of 79.1%. In particular, the Fe-NMCNF sample calcined at 800 °C exhibits both excellent catalytic activity for oxygen reduction reaction and superb long-term stability compared to commercial Pt/C in acid electrolyte of 0.1 M HClO₄. The performance improvement results from the combined effect of the well-dispersed Fe nanoparticles exposed within N-doped mesoporous CNFs and the uniform morphology of mesoporous CNFs.