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 & horbar;N & horbar;C catalysts. Herein, an efficient single metallic Mn active site is constructed to improve the strength of the Fe & horbar;N bond, inhibiting the demetalation effect of Fe & horbar;N & horbar;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 & horbar;N bond and inhibiting the electrochemical dissolution of Fe. The oxygen reduction reaction pathway for the dissociation of Fe & horbar;Mn dual sites can overcome the high energy barriers to direct O & horbar;O bond dissociation and modulate the electronic states of Fe & horbar;N4 sites. The resulting FeMn & horbar;N & horbar;C exhibits excellent ORR activity with a high half-wave potential of 0.92 V in alkaline electrolytes. FeMn & horbar;N & horbar;C as a cathode catalyst for Zn-air batteries has a cycle stability of 700 h at 25 degrees C and a long cycle stability of more than 210 h under extremely cold conditions at -40 degrees C. These findings contribute to the development of efficient and stable metal-nitrogen-carbon catalysts for various energy devices. Mn acts as an electron donor to reduce the oxidation state of Fe by increasing the electron density at the Fe & horbar;N4 site, thereby strengthening the Fe & horbar;N bond and inhibiting the electrochemical dissolution of Fe. As a result, FeMn & horbar;N & horbar;C exhibits excellent discharge performance and stability in Zn-air batteries. image