Low-Cost Synthesis of Atomically Dispersed Fe–Mn Dual-Site Single-Atom Catalysts for Oxygen Reduction in Zn–Air Batteries

Single-atom-based electrocatalysts have gained widespread interest due to their effectiveness in promoting the oxygen reduction reaction (ORR). Single-atom electrocatalysts remain limited in application due to their reliance on costly and complex materials and fabrication processes. Herein, we introduce an inexpensive general complexation–pyrolysis-based route for the mass production of Fe1Mn1/NC, an atomically dispersed bimetallic electrocatalyst. 1,10-Phenanthroline (phen), functioning as both a metal-complexing ligand and nitrogen source, was combined with inexpensive BP 2000 carbon black used as the carbon matrix. A homogeneous dispersion of Fe2+, Mn2+, and 1,10-phenanthroline with BP 2000 carbon black was prepared in methanol, followed by solvent removal and subsequent pyrolysis, which enabled the generation of a high density of MNx active centers within the carbonaceous matrix. The synthesized Fe1Mn1/NC electrocatalyst exhibited remarkable oxygen reduction performance, as evidenced by half-wave potentials of 0.936 V in 0.1 M KOH and 0.78 V in 0.1 M HClO4. Furthermore, when applied as the cathodic electrocatalyst in a Zn–air battery, Fe1Mn1/NC enabled a remarkable performance output, including a peak power density of 189 mW cm–2, a specific capacity of 781.2 mA h gZn–1, and prolonged operational durability beyond 400 h. This study revealed that inexpensive raw materials are capable of generating highly catalytically active sites under appropriate conditions.