Consolidating the Oxygen Reduction with Sub-Polarized Graphitic Fe–N4 Atomic Sites for an Efficient Flexible Zinc–Air Battery

The effectuation of the Zn–air battery (ZAB) is appealing for active and durable catalysts to kinetically drive the sluggish cathodic oxygen reduction reaction (ORR). Atomic metal-N_x-C sites are widely witnessed with Pt-like activity, but their demetalations still severely restrict the durability in ORR. Here we have profiled an ordered hierarchical porous carbon supported Fe–N₄ single-atom (FeNC) catalyst by a template derivation method for efficient ORR and flexible ZAB studies. The FeNC structure is observed with a sub-polarized graphitic Fe–N₄ coordination with a shortened Fe–N bond for potentially consolidating the ORR, together with the hierarchical porous matrix for kinetical mass transfer. Resultantly, the optimized FeNC catalyst showcases Pt-beyond alkaline ORR activity (E_1/2 = 0.95 V) with long-term durability for 100 h, delivering the flexible ZAB device with high power density (251 mW cm^–2) and durable cycle life (80 h). This research underscores the criterion in rationalizing active and robust ORR catalysts through metal–nitrogen bond modulation.