CoFePx/FeCo@PNCF Nanofibers Featuring PS-Induced Open Channels for Enhanced ORR/OER Performance in Rechargeable Zinc–Air Batteries

Developing efficient Zn-air battery (ZAB) cathode catalysts is key to driving their commercialization process and tackling the pressing issues of environmental pollution and energy scarcity. Modulating the electronic structure and micronano configuration to expose more active sites is expected to boost the catalysts' electrochemical activity. Among different materials, one-dimensional (1D) carbon composite materials offer distinct advantages in electrocatalysis. Nevertheless, a common challenge is that conventional electrospinning synthesis often results in inaccessible metal active sites due to the rapid prototyping and solidification of the polymer slurry under an electric field. Herein, the polystyrene (PS)-induced electrospinning strategy is employed to fabricate porous composite carbon nanofibers (CoFePx/FeCo@PNCF) assisted by phosphating pyrolysis. This approach integrates polystyrene (PS) nanospheres as stents within the carbon nanofibers, thereby creating open channels and preventing the aggregation of nanoparticles, ensuring optimal functionality. The resulting CoFePx/FeCo@PNCF catalysts, which feature abundant pores near the metal nanoparticles, exhibit superior oxygen reduction reaction-oxygen evolution reaction (ORR-OER) activity, achieving a small potential gap of 0.648 V. Density functional theory (DFT) calculations demonstrate electron redistribution following heterojunction formation, with the electron localization function (ELF) confirming the localized electron density. The aqueous ZABs assembled with CoFePx/FeCo@PNCF cathodes deliver a high peak power density (183.40 mW cm^-2), high specific capacity (791.20 mAh g^-1), robust initial discharge capability (>300 h), and stability upon cycling (∼563 h, ∼1690 cycles). The solid-state ZABs demonstrate strong performance, and two devices sustain a 2.5 V light-emitting diode (LED) lamp for over 7 days.