Unraveling Cathodic Defect-Electric Field Synergism in the Enhanced Electroactivation of Peroxydisulfate for Highly Efficient Removal of Emerging Contaminants

Abstract Cathodic electroactivation of peroxydisulfate (PDS) provides a sustainable pathway for treating emerging contaminants, yet the rational design of cathode interfaces to maximize electric field synergy remains a critical challenge. Herein, this study prepared a modified carbon felt cathode with defective D-MIL-88B(Fe) (D-MOF/CF) containing coordinatively unsaturated Fe sites (Fe CUS) and oxygen vacancies (OV), which showed greatly enhanced effectiveness for the electroactivation of PDS to remove sulfamethoxazole. Experimental characterization and theoretical calculations revealed that the electric field cooperated with OV to induce local charge rearrangement, thereby modulating the local electronic structure and d-band center of Fe CUS, lowering the thermodynamic barrier for reactive species generation and simultaneously enhancing the Fe2+/Fe3+ cycling efficiency. This defect-electric field synergy substantially accelerated PDS activation kinetics, yielding high steady-state concentrations of ·OH (5.96 × 10–10 M) and SO4·– (3.55 × 10–10 M) in the reaction process of the E-D-MOF/CF-PDS system and achieving 100% SMX removal with an electrical energy per order of 0.094 kWh m–3 order–1. In addition, the system exhibited promising preliminary stability in continuous operation and effectiveness in treating real mariculture tailwater to meet discharge standards with low energy consumption. This study established a site-specific electric-field modulation framework, offering a generalizable strategy for designing efficient electrocatalytic interfaces toward sustainable water remediation.