Hollow Porous Nitrogen‐Doped Carbon‐Confined FeP/Fe 2 P Nanoparticle‐Armored Catalyst for Efficient Oxygen Reduction Reaction in Aqueous/Flexible Zinc‐Air Batteries

Abstract

ABSTRACT The design of nanoparticles confined in hollow N‐doped carbon structures is crucial for improving the oxygen reduction reaction (ORR) kinetics, yet achieving this remains a significant challenge. In this work, hollow porous nitrogen‐doped carbon encapsulated FeP/Fe 2 P (H‐FeP/Fe 2 P) were successfully constructed via a templating method combined with dopamine hydrochloride coating, acid etching, and subsequent high‐temperature phosphating. In situ spectroelectrochemical investigations and theoretical results demonstrate that the adsorbed hydroxyl species (*OH) can be readily released from the catalyst surface by facilitating the dissociation of oxygen–oxygen bonds at the active sites of Fe, thus accelerating the kinetics of the ORR. The optimized H‐FeP/Fe 2 P achieves a high limiting current density of 5.5 mA cm −2 and a low Tafel slope of 39 mV dec −1 in 0.1 M KOH, outperforming corresponding solid samples and most reported transition metal phosphide catalysts. Moreover, the H‐FeP/Fe 2 P‐based aqueous ZAB exhibits remarkable performance, including high peak power density (175 mW cm −2 ), large specific capacity (813 mAh g −1 Zn ), and stable charge/discharge stability over 800 h. The corresponding solid‐state zinc‐air battery also delivers a high peak power density of 101 mW cm −2 and excellent flexibility. The carbon confinement strategy proposed in this study opens new avenues for developing high‐performance and cost‐effective non‐precious metal ORR catalysts in zinc‐air batteries.