Electron push-pull engineered Fe-Co dual-atom hollow nanofiber membranes drive super-efficient and sustainable...

Electrocatalytic membranes that integrate oxygen reduction reactions with membrane filtration present a promising and chemical-free approach for electro-Fenton (EF) water treatment. However, its efficient and continuous production of ·OH radicals remains challenging due to the difficulty in maintaining both high catalytic activity and long-term stability of the electrocatalysts required for the two key EF steps: H₂O₂ generation and activation. To overcome this challenge, Fe-Co dual-atom catalysts were embedded within porous hollow carbon nanofibers (HCNF) to fabricate a novel nanoconfined electrocatalytic Fe-Co-HCNF membrane. Operating as a flow-through membrane cathode at -0.6 V vs. RHE, the reactive membrane achieved about 99% removal of tetracycline at a flux of ∼1000 L m^-2 h^-1, with a retention time of 1.04 s and a very low energy consumption of 0.05 kWh m^-3 order^-1 for over 1000 h. DFT and MD calculations revealed that the Fe-Co-HCNF membrane synergistically optimizes the binding energies of intermediates ·OOH and *H₂O₂, facilitating rapid H₂O₂ generation and activation. Moreover, an intrinsic electron push-pull effect between Fe-N₄ and Co-N₄ dual sites underpins the electron-driven Co(III)/Co(II) redox cycle, which chemically promotes the Fe(III)/Fe(II) cycle by facilitating directional electron transfer, enabling continuous regeneration of Fe(II) to sustain the EF process. By eliminating both the iron sludge inherent in conventional Fenton processes and the concentrated retentate of membrane filtration, this strategy establishes a highly efficient, cost-effective, and green paradigm for sustainable water purification.