Inhibiting Demetalation of Fe-N-C via Mn Sites for Efficient Oxygen Reduction Reaction in Zinc-Air Batteries.

Demetalation caused by the electrochemical dissolution of metallic Fe atoms is a major challenge for the practical application of Fe-N-C catalysts. Herein, we construct an efficient single metallic Mn active site to improve the strength of the Fe-N bond, inhibiting the demetalation effect of Fe-N-C. Mn acts as an electron donor inducing more delocalized electrons to reduce the oxidation state of Fe by increasing the electron density, thereby enhancing the Fe-N bond and inhibiting the electrochemical dissolution of Fe. The ORR pathway for the dissociation of Fe-Mn dual sites can overcome the high energy barriers to direct O-O bond dissociation and modulate the electronic states of Fe-N 4 sites. The resulting FeMn-N-C exhibits excellent ORR activity with a high half-wave potential (E 1/2 ) of 0.92 V in alkaline electrolytes. FeMn-N-C as a cathode catalyst for Zn-air batteries (ZABs) has a cycle stability of 700 h at 25 °C and a long cycle stability of more than 210 h under extremely cold conditions at -40 °C. These findings contribute to the development of efficient and stable metal-nitrogen-carbon catalysts for various energy devices. This article is protected by copyright. All rights reserved.