Mitigating free radical corrosion of Fe-N-C catalysts by single-atom rare earth for durable oxygen reduction reaction

Developing durable non-precious metal catalysts for the oxygen reduction reaction (ORR) is essential to address the stability challenges of conventional Fe-N-C systems, which suffer from reactive oxygen species (ROS) corrosion caused by H 2 O 2 by-product. Herein, we report an atomically dispersed Sm–Fe dual-atom catalyst (SmFe-N-C), synthesized by pyrolyzing a nitrogen-rich precursor templated with hierarchical SiO 2 . The catalyst features isolated Sm and Fe sites anchored on porous N-doped carbon, forming a bifunctional architecture: Fe sites act as the primary ORR centers, while Sm sites serve as radical scavengers to suppress Fenton-induced degradation. Spectroscopic and theoretical studies reveal that Sm sites inhibit ROS formation and diffusion while promoting their scavenging, thereby enhancing catalyst durability. Moreover, Sm incorporation induces asymmetric charge redistribution around Fe atoms, optimizing the adsorption behavior of oxygen intermediates and accelerating ORR kinetics. The SmFe-N-C catalyst delivers a half-wave potential of 0.899 V (vs. RHE) and a kinetic current density of 5.52 mA cm −2 at 0.9 V, outperforming Fe-N-C and Sm-N-C counterparts. It retains 98% of its current over 20 h and delivers a peak power density of 129.2 mW cm −2 in Zn–air batteries over 60 h cycling. This work demonstrates the promise of rare-earth dual-atom modulation for stable, high-performance ORR catalysis. • A multi-level-porous SiO 2 template strategy was utilized to prepare dual single-atom SmFe-N-C catalysts. • Sm mitigates the substantial generation of free radicals induced by Fe, preventing catalyst deactivation during ORR reactions. • Sm incorporation induces asymmetric charge redistribution around Fe atoms, optimizing the adsorption behavior of ORR intermediates and enhancing ORR kinetics. • The obtained SmFe-N-C possesses promising ORR performance and excellent stability. • A primary Zn-air battery using SmFe-N-C as the cathode catalyst surpassed that of a battery constructed with Pt/C.