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 MnL+-N-4 is the active site during the oxygen reduction process. Density functional theory reveals that facile electron transfer from MnL+-N-4 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-N-4 material shows high power density and excellent durability, demonstrating its promising potential to substitute the Pt catalyst in practical devices.