Fe₃Co nanoparticles embedded carbon nanotube complex as effective bifunctional electrocatalysts for rechargeable zinc-air batteries

Fe₃Co nanoparticles have been successfully embedded within ZIF-8 derived carbon nanotube complex using a simple solvent-heated self-assembly-pyrolysis strategy, it acts as an efficient ORR/OER bifunctional electrocatalyst and showed outstanding performance of excellent catalytic activity for ORR (E_1/2 = 0.87 V at 0.1 M KOH) and OER (the overpotential at 10 mA cm⁻² is 390 mV at 1 M KOH). Density functional theory (DFT) demonstrates that the introduction of iron and cobalt atoms significantly impacted on the adsorption energies of the reactive intermediates. In particular, the combination of cobalt and iron exhibited significantly enhanced ORR/OER activities, revealing an enhanced effect of synergistic interaction of FeCo site for bifunctional properties. It is used as Fe₃Co₁−NC in aqueous zinc-air battery (ZAB) and exhibited a high open-circuit voltage of 1.52 V, power density of 189.8 mW cm⁻², and long cycle durability of 400 h. Flexible ZABs assembled exhibit high power density (81.59 mW cm⁻²) and long cycling durability (90 h).