Thermally-Driven ZnO-Mediated Atomization of FeCu _<i>x</i> 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–N4 moieties generally suffer from unsatisfactory intrinsic activity and durability. Herein, iron–copper oxide nanoparticles (FeCuxO NPs) were transformed into trimetallic atomic electrocatalysts containing atomically dispersed iron, copper, and zinc on N-doped carbons (FeZnCux-NC) via an in situ encapsulation and ZnO-mediated pyrolysis strategy. The introduction of Zn and Cu atoms modulates the electronic environment of traditional FeN4 sites, optimizing the adsorption and desorption of reaction intermediates and lowering the theoretical overpotentials of ORR. Benefiting from the unique configuration of dual-atom FeZnN6 sites and nearby CuN4 sites, a compositionally optimized FeZnCu0.05-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 FeZnCu0.05-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.