Mesopore-tuned iron and nitrogen co-doped carbon for enhanced oxygen reduction electrocatalysis
Pore-tuning engineering is an effective strategy for designing catalysts for energy storage and conversion. Here, we report a rhombic dodecahedral iron and nitrogen co-doped carbon (Fe-N-C) material with hierarchical micro-mesoporous structures, synthesized using mesoporous silica as both pore template and iron source. The resulting catalyst (m-Fe/NC) exhibits significantly enhanced oxygen reduction reaction (ORR) activity, with half-wave potentials of 0.81 V and 0.88 V in acidic and alkaline media, respectively. When employed as a cathode in zinc-air batteries, m-Fe/NC delivers a superior specific capacity of 815 mAh g_Zn^-1 and a stable cell voltage of 1.31 V at a current density of 10 mA cm^-2. Advanced characterization and theoretical calculations reveal that the mesoporous structure not only increases active site exposure but also induces a curvature-induced strain effect on concave surfaces, which enhances intrinsic activity. This work provides insights for developing innovative nanoporous electrocatalysts.