Mn-N₄ Oxygen Reduction Electrocatalyst: Operando Investigation of Active Sites and High Performance in Zinc–Air Battery

The development of inexpensive and highly efficient nonprecious metal catalysts to substitute Pt in the alkaline oxygen reduction reaction is an appealing idea in the energy field. Herein, a Mn oxygen reduction electrocatalyst with a half-wave potential (E_1/2) as high as 0.910 V under an alkaline oxygen reduction reaction process is developed, and the dynamic atomic structure change of the highly efficient Mn single-atomic site is investigated using operando X-ray absorption spectroscopy. These results demonstrate that the low-valence Mn^L+-N₄ is the active site during the oxygen reduction process. Density functional theory reveals that facile electron transfer from Mn^L+-N₄ to adsorbed *OH species plays a key role in the excellent electrocatalytic performance. Moreover, when assembled as the cathode in a zinc–air battery, this Mn-N₄ material shows high power density and excellent durability, demonstrating its promising potential to substitute the Pt catalyst in practical devices.