Bifunctional cobalt//nickel-iron@carbon nanofiber electrocatalyst with spatially separated dual active sites for advanced zinc-air batteries

Sluggish oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) reaction kinetics restrict the application of zinc-air batteries, making the exploration of high-performance bifunctional electrocatalysts imperative. Here, a multiple synergistic strategy is proposed to fabricate Co//NiFe@CNFs composite with spatially separated dual-active-sites, with NiFe nanoparticles encapsulated inside carbon fibers and Co nanoparticles anchored on their outer surfaces. The catalyst exhibits excellent bifunctional catalytic activity with a high ORR half-wave potential of 0.865 V (vs. RHE) and a low OER overpotential of 310 mV at 10 mA cm −2 . Meanwhile, the Co//NiFe@CNFs catalyst shows excellent durability with a current retention rate of 95.41% after 35,000 s and methanol tolerance. The assembled zinc-air battery achieves a peak power density of 145.6 mW cm −2 at 231.9 mA cm −2 and a specific capacity of 815 mAh g Zn −1 at 10 mA cm −2 , and excellent cycling stability. The excellent electrocatalytic performance originates from multifactor synergy that the porous fibrous structure accelerates mass transport, Co and NiFe nanoparticles provide abundant active sites, and their spatial separation improves structural stability while eliminating cross-interference between active centers for different catalytic pathways.