Boosting Oxygen Reduction Catalysis on Fe─N─C via Long-Range Electronic Metal-Support Interaction from Ultrasmall...

Single-atom Fe─N─C catalysts are promising alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR), yet their performance is often limited by insufficient electronic modulation of the isolated Fe─N₄ sites. Herein, we develop a facile chemical vapor deposition approach to synthesize a Fe─N─C catalyst (denoted as FF/Fe─NC) that simultaneously incorporates surface-accessible Fe/Fe₂O₃ nanoparticles (∼1.0 nm) and atomically dispersed Fe─N₄ sites. In alkaline media, FF/Fe─NC delivers a superior 4-electron ORR activity with a half-wave potential of 0.92 V (vs. RHE) and a high turnover frequency (1.8 s^-1 at 0.9 V), significantly outperforming Fe/Fe₂O₃-free sample (Fe─NC) and commercial Pt/C. When employed as a cathode in a zinc-air battery, FF/Fe─NC delivers a high peak power density (218 mW cm^-2) and outstanding cycling stability. The enhanced performance is primarily attributed to the long-range electronic metal-support interaction (LR-EMSI) between Fe/Fe₂O₃ nanoparticles and Fe─N₄ sites, which effectively optimizes the adsorption of reaction intermediates and accelerates the overall ORR kinetics. This work provides an effective design strategy for boosting the performance of metal and nitrogen co-doped carbon catalysts through the rational integration of metal nanoparticles and single-atom sites.