FeCo Bimetallic Alloy Nanoparticles Embedded in Nitrogen-Doped Porous Carbon for Effective Oxygen Reduction in Zinc–Air Batteries

The rational design and simple preparation of non-noble metal catalysts for the oxygen reduction reaction (ORR) are urgently needed for mass commercial full-cell applications, but many challenges still exist. Herein, FeCo bimetallic alloy nanoparticles in nitrogen-doped dodecahedral porous carbon (FeCo-NC) with a controllable microstructure and catalytic efficiency are prepared by the secondary carbonization method using ZIF-67 as the self-sacrificial template and pore former and FeCl3 as the activated metal source. By adjusting the amount of FeCl3·6H2O to 60 mg, the prepared catalyst (FeCo-NC-60) exhibits an optimal configuration characterized by a multilayered porous structure, a significant specific surface area, and a substantial abundance of active centers (pyridinic nitrogen, graphitic nitrogen, and Fe–Nx). Therefore, the FeCo-NC-60 catalyst has an excellent catalytic effect in 0.1 M KOH, and its half-wave potential is as high as 0.874 V, which exceeds that of commercial Pt/C by about 20 mV. Furthermore, a zinc–air battery that was created using FeCo-NC-60 as the air cathode demonstrates notable characteristics such as a substantial open-circuit voltage of 1.473 V, an impressive specific capacity of 703 mA h g–1 at 10 mA cm–2, and exceptional reversible porperties and stability. This synthesis method takes into account the ORR catalytic activity and enhances the stabilization of the fabricated catalysts. It offers a strategy for accomplishing bimetal doping and enhancing the active sites of M–Nx (M = Fe, Co).