Bifunctional flow-through electrified-membrane for intensified confined hydroxyl radical generation and efficient pollutant degradation

Flow-through electro-Fenton (FTEF) membrane system is a promising wastewater treatment technology that synergistically integrates electrocatalytic reactions with enhanced mass transport to promote pollutant degradation. However, existing studies have not elucidated the dynamic interplay and balance between hydrogen peroxide (H 2 O 2 ) generation and in situ activation, thereby limiting effective reactive oxygen species production. In this study, we develop a bifunctional electrified membrane composed of surface-engineered carbon nanotubes (CNT S ) for spontaneous H 2 O 2 production and Fe 3+ reduction to facilitate hydroxyl radical (•OH) generation. Through a combination of in situ Fourier-transform infrared spectroscopy, density functional theory calculations, and quantitative active site reactivity analysis, BC 2 O and C O moieties are identified as the dominant sites for O 2 and Fe 3+ reduction, respectively. Under optimized conditions, the produced H 2 O 2 at BC 2 O sites is activated by Fe(II) generated at adjacent C O sites, resulting in abundant confined •OH that leads to 93.4 % acyclovir degradation via FTEF, compared to 30.1 % removal in the batch mode. Furthermore, the catalytic FTEF system maintains ≥90 % acyclovir removal over 10 cycles and exhibits broad applicability for degrading diverse organic pollutants. This work provides a facile and controllable FTEF system for driving electrified water treatment via molecular and reactor-level engineering. • Boron/oxygen co-doped carbon nanotubes for O 2 and Fe 3+ reduction separately. • Flow-through electrified membrane enhances tri-phase O 2 and Fe 3+ mass transfer. • Potential control balances H 2 O 2 synthesis and Fe 3+ reduction to maximize •OH yield. • Three kinds of •OH were analyzed by qualitative and qualitative methods.