Nano‐Stabilizer Engineering of Rare‐Earth Metal Single‐Atom Site for Boosted Oxygen Electroreduction and Metal‐Air Batteries

ABSTRACT Stabilizing the coordination structure of highly active catalytic sites is an effective strategy for enhancing catalytic performance. Herein, rare‐earth metal Pr‐based single‐atom nano‐stabilizer engineering is reported for stabilizing highly active Fe‐N 4 O sites, thereby achieving enhanced activity toward the oxygen reduction reaction and in metal‐air batteries. In situ x‐ray absorption spectroscopy reveals that the axial O coordination atom of the Fe‐N 4 O site is stabilized by the Pr single‐atom nano‐stabilizer, which downshifts the d‐band center of Fe, facilitates the reduction and desorption of the *OH intermediate, and thus lowers the energy barrier of the rate‐determining step—verified via density functional theory calculations. The FePr‐ISAS/CN catalyst with the nano‐stabilizer exhibits a half‐wave potential of 0.921 V versus RHE, 45 and 72 mV higher than those of Fe‐ISAS/CN and the commercial Pt/C catalyst. Furthermore, the FePr‐ISAS/CN‐based Al‐air battery achieves a high peak power density of 360 mW cm −2 , superior to most reported metal single‐atom catalyst‐based Al‐air batteries. This work reveals the potential of rare‐earth metal‐based nano‐stabilizer engineering for stabilizing the coordination structure of highly active sites and thereby boosting activity in both electrocatalytic ORR and metal‐air battery devices.