CoFe Formic Acid Framework-Derived Co ₇ Fe ₃ /Co/Co ₂ P Composite N, P-Doped Carbon as Bifunctional Electrocatalyst for Zinc–Air Batteries

The development of rechargeable zinc-air batteries is critically hindered by the sluggish kinetics of both the oxygen reduction and the oxygen evolution reaction. For advancing zinc-air battery technology. The effective design of bifunctional catalysts that efficiently facilitate both the oxygen reduction and oxygen evolution reactions is crucial for advancing the development of zinc-air batteries. Overcoming the intrinsic sluggish kinetics of oxygen electrocatalysis remains a fundamental challenge that limits the commercial viability of rechargeable zinc-air batteries. Herein, the work proposes a rational strategy to construct a three-phase heterogeneous interface: Co₇Fe₃/Co/Co₂P@NPCNT was successfully synthesized by a two-step pyrolysis using CoFe-FF as the precursor and dicyandiamide and sodium hypophosphite as carbon, nitrogen, and phosphorus sources, respectively. The half-wave potential (E1/2) of Co₇Fe₃/Co/Co₂P@NPCNT is 0.85 V, and the overpotential (η₁₀) is 295 mV at 10 mA cm⁻². Comparative evaluation confirms that the catalytic activity of Co₇Fe₃/Co/Co₂P@NPCNT is superior to those of Pt/C and RuO₂. The catalytic activity of Co₇Fe₃/Co/Co₂P@NPCNT is superior to that of Pt/C and RuO₂. Meanwhile, the zinc-air batteries assembled by Co₇Fe₃/Co/Co₂P@NPCNT have an open-circuit voltage of 1.45 V, a peak power density of 130 mW cm⁻², and a large specific capacity. The structure of carbon nanotubes not only facilitates the dispersion of metal nanoparticles but also increases the active sites. Moreover, the corrosion of nanoparticles by alkaline electrolyte is reduced, and the stability is enhanced. The good bifunctional catalytic activity of Co₇Fe₃/Co/Co₂P@NPCNT can be attributed to the synergistic effect of electron transfer between the three-phase interfaces and the multicomponent active centers (alloy, phosphide, N, P-codoped carbon nanotubes). In this work, the three-phase heterogeneous interface is constructed reasonably. This unique structure improves the catalytic activity and provides a new idea for the design of bifunctional catalysts.