Thermally-Driven ZnO-Mediated Atomization of FeCu x O Nanoparticles into FeZnCu Trimetallic Atomic Sites for the Oxygen Reduction Reaction

Fe–N–C catalysts have emerged as promising alternatives to platinum-based electrocatalysts for the oxygen reduction reaction (ORR). However, single Fe–N 4 moieties generally suffer from unsatisfactory intrinsic activity and durability. Herein, iron–copper oxide nanoparticles (FeCu x O NPs) were transformed into trimetallic atomic electrocatalysts containing atomically dispersed iron, copper, and zinc on N-doped carbons (FeZnCu x -NC) via an in situ encapsulation and ZnO-mediated pyrolysis strategy. The introduction of Zn and Cu atoms modulates the electronic environment of traditional FeN 4 sites, optimizing the adsorption and desorption of reaction intermediates and lowering the theoretical overpotentials of ORR. Benefiting from the unique configuration of dual-atom FeZnN 6 sites and nearby CuN 4 sites, a compositionally optimized FeZnCu 0.05 -NC electrocatalyst delivered a half-wave potential of 0.92 V in 0.1 M KOH electrolyte, outperforming a commercial Pt/C catalyst and most state-of-the-art ORR electrocatalysts. A zinc-air battery constructed with FeZnCu 0.05 -NC as the air-cathode catalyst delivered a specific capacity of 806 mAh g –1 and charge–discharge stability over 1500 h. This work offers a simple strategy for synthesizing polymetallic atom electrocatalysts with high ORR activity and excellent durability.