• • The m-Fe/NC catalyst achieves half-wave potentials of 0.81 V (acidic) and 0.88 V (alkaline), outperforming many non-precious metal catalysts and approaching Pt/C performance, critical for fuel cell and metal-air battery efficiency.
• • In zinc-air battery tests, m-Fe/NC delivers a specific capacity of 815 mAh g_Zn^-1 and a stable cell voltage of 1.31 V at 10 mA cm^-2, indicating high energy density and operational stability for practical applications.
• • Turnover frequency (TOF) for acidic ORR at 0.8 V is 0.26 s^-1 for m-Fe/NC-2, compared to 0.064 s^-1 for microporous Fe/NC, a 4-fold improvement, demonstrating enhanced intrinsic activity due to mesoporosity.
• • Density functional theory (DFT) calculations show that Fe-N4 sites on mesoporous surfaces have lower energy barriers (0.66–0.69 eV) for ORR than microporous Fe/NC-1 (0.72 eV), confirming the curvature-induced strain effect weakens intermediate adsorption and facilitates 4e^- reduction.