Modulated FeCo nanoparticle in situ growth on the carbon matrix for high-performance oxygen catalysts

Fe–Co bimetallic electrocatalysts show tremendous promise for both oxygen reduction reaction (ORR) and oxygen evolution reaction in the alkaline medium to replace precious metal catalysts. Here, we report a successful size modulation strategy for FeCo binary alloys in situ growth on the carbon matrix. Analogous to Pt nanoparticles, the size modulation could give rise to increased active sites in FeCo-based catalysts without altering their chemical properties. The compositionally optimized template with abundant carbon nanotubes and uniform distribution of FeCo alloy nanoparticles, exhibits superior electrocatalytic activity by achieving a high-performance half-wave potential of 0.88 V toward ORR as well as robust stability after 10 000 cycles. The open-circuit potential (Voc) of the liquid Zn–air battery is close to 1.40 V which is comparable with that of the Zn–air battery equipped with Pt/C+IrO₂. Our findings offer new prospects for understanding metal particle sizes and electrocatalytic performance of pyrolyzed transition metal–carbon materials.