• • Fe−N−PCG achieves a site density (SD) of 2.74×10^19 sites g−1 and Fe utilization (UFe) of 51.7%, significantly enhancing active site exposure compared to conventional Fe−N−C catalysts, which typically suffer from buried sites and utilization below 20%. This directly translates to higher volumetric activity and reduced catalyst loading in practical devices.
• • In a half-cell configuration, Fe−N−PCG exhibits a mass transport overpotential (ηmt) of only 67 mV at 800 mA cm−2, demonstrating superior mass transport efficiency under high current densities where conventional catalysts are limited by diffusion. This enables operation at industrially relevant current densities without excessive voltage loss.
• • Zinc-air battery tests show Fe−N−PCG delivers a peak power density of 296.1 mW cm−2 at 500 mA cm−2, exceeding Pt/C (241 mW cm−2 at 438 mA cm−2) and control samples (Fe−N−CG: 283 mW cm−2, Fe−N−PG: 255 mW cm−2, Fe−N−G: 239 mW cm−2). This high power density is critical for high-rate applications such as electric vehicles and grid storage.
• • At a galvanostatic discharge of 50 mA cm−2, Fe−N−PCG provides a specific capacity of 815 mAh g−1 and a discharge voltage of 1.19 V, outperforming Pt/C (715 mAh g−1, 1.13 V). The higher capacity and voltage under load indicate improved energy efficiency and longer operational lifetime, essential for commercial viability.