Highly exposed surface pore-edge FeNx sites for enhanced oxygen reduction performance in Zn-air batteries

Single Fe atoms with N-coordination (FeNx sites) in Fe-N-C catalysts are widely recognized as the active centers for catalyzing oxygen reduction reaction (ORR), but attaining superior intrinsic activity and more exposure of the FeNx sites remains challenging. Herein, the surface pore-edge FeNx sites anchored on suitable porous carbon (SPE-FeNx-HPNC) are reported, which could simultaneously enhance the intrinsic activity and more exposed active sites for ORR. Theoretical calculations suggest that pore-edge FeNx sites are more active than pure FeNx sites in the rate-determining step, hence promoting the intrinsic ORR activity of active sites. Therefore, due to abundant surface pore-edge FeNx sites and beneficial pore structures, SPE-FeNx-HPNC exhibits excellent ORR activity with a half-wave potential (E-1/2) of 0.902 V in an alkaline medium. Moreover, the assembled Zn-air battery with SPE-FeNx-HPNC delivers a peak power density of 150 mW cm(-2) and a durable charge-discharge cycle over 450 hours. This work provides an effective strategy for preparing a high-performance catalyst for Zn-air batteries.