Morphology reconstruction of porous FeCo–carbon microspheres for efficient bifunctional electrocatalysis

Carbon-based transition-metal electrocatalysts with one-dimensional porous nanofibrous architectures generally exhibit favorable electrical conductivity and abundant exposed defects, making them attractive for bifunctional electrocatalysis. However, densely stacked fibrous networks often suffer from sluggish electrolyte infiltration and inefficient gas escape, while transition-metal species are also prone to aggregation during high-temperature treatment, resulting in insufficient active-site utilization and restricted catalytic performance. In this work, a morphology-reconstruction strategy is developed to fabricate hierarchically porous FeCo–carbon microspheres for efficient bifunctional electrocatalysis in alkaline media. A formamide-assisted FeCo coordination precursor, together with a PTFE-containing electrohydrodynamic system, which induces jet breakup via Rayleigh instability and enables an in situ transition from conventional continuous fibers to three-dimensional porous microspheres. The obtained FA-FeCo@PMS catalyst consists of highly dispersed FeCo species embedded within a defect-rich N/O/P-doped porous carbon framework. Benefiting from the reconstructed porous microsphere architecture and the homogeneous distribution of active species, FA-FeCo@PMS exhibits enhanced electrolyte accessibility, facilitated gas diffusion, and improved interfacial charge-transfer behavior. Electrochemical measurements in 1.0 M KOH demonstrate that FA-FeCo@PMS delivers overpotentials of 300 and 350 mV at 10 and 50 mA cm −2 for the oxygen evolution reaction, respectively, together with an HER overpotential of 175 mV at 10 mA cm −2 , as well as satisfactory long-term durability and low charge transfer resistance. This work provides a feasible strategy for simultaneously regulating catalyst morphology and active-species dispersion toward efficient bifunctional electrocatalysis.