Atomic Modulation and Structure Design of Fe?N_4 Modified Hollow Carbon Fibers with Encapsulated Ni Nanoparticles for Rechargeable Zn–Air Batteries

摘要

Excellent bifunctional oxygen reduction reaction (ORR)/oxygen evolutionreaction (OER) activity and rapid mass transport capability are two importantparameters of electrocatalysts for high-performance rechargeable Zn–airbatteries (ZABs). Herein, an efficient atomic modulation and structure designto promote bifunctional activity and mass transport kinetics of an ORR/OERelectrocatalyst are reported. Specifically, atomic Fe?N_4 moieties are immobilizedon premade hollow carbon fibers with encapsulated Ni nanoparticles(Fe-N@Ni-HCFs). Synchrotron X-ray absorption spectroscopy and sphericalaberration-corrected electron microscope analyses confirm the atomic distributionof the active sites and unique lung bubble-like hollow architecture ofthe catalyst, while theoretical investigations reveal that the encapsulated Ninanoparticles can induce electron distribution of the atomic Fe?N4 moietiesto reduce reaction energy barriers. As a result, the prepared catalystpossesses enhanced bifunctional ORR/OER activity and well-constructedgas–solid–liquid interfaces for improved mass transfer. These synergeticadvantages endow the binder-free Fe-N@Ni-HCFs electrode with the remarkablepower density and cycling stability for ZABs, outperforming the commercialPt/C+Ir/C benchmark. This exceptional performance suggests that theproposed strategy can be extended to the design and fabrication of electrocatalystsfor energy conversion and storage.