Local Single Co Sites at the Second Shell of Fe‐N₄ Active Sites to Boost Oxygen Reduction Reaction

Abstract

Fe single‐atom catalysts (SACs) are a promising catalyst for oxygen reduction reaction (ORR) in both Zn–air batteries (ZABs) but have a certain distance to compete with Pt‐based catalysts. Rational modulation of the coordination environment in the second coordination shell of SACs offers an opportunity to improve the intrinsic ORR activity, yet a challenge. Here, a novel strategy is reported to construct a dual‐metal catalyst by introducing a single Co atom in the second coordination shell of the Fe center. The dual‐metal N₃─Fe─N─Co site with a certain Fe─Co distance of 0.312 nm is constructed. It allows for manipulation of the positive shift of the Fe center charge state, driving the d‐band center up‐shift by 0.63 eV, thereby offering the optimal adsorption of intermediates. Benefiting from this structure, the as‐prepared Fe(Co_2nd)‐NC enables an excellent ORR activity with a half‐wave potential of 0.948 V in 0.1 

KOH. As a cathode in ZABs, it delivered an outstanding peak power density of 218 mW cm⁻² and a specific capacity of 915 mAh g_Zn⁻¹ at 5 mA cm⁻², respectively, with superior long‐term durability over 680 h. The second shell layer alignment regulation strategy shows great potential for energy storage applications.