Enhancing electrochemical reductive defluorination of PFASs using ZIF-67 modified cathode : Mechanistic insights and performance optimization

Summary

The effectiveness of electrochemical reductive defluorination is impeded by the low environmental concentrations of per- and polyfluoroalkyl substances (PFASs) and the robust nature of C − F bonds. In this work, we investigate the zeolitic imidazolate framework-67 (ZIF-67) as a promising catalyst for PFASs remediation. We show that ZIF-67 hold promise for simultaneous adsorption and reductive defluorination of 2-(trifluoromethyl) acrylic acid (TFMAA). Following a 48-hour treatment, the ZIF-67 modification significantly improves the adsorption of TFMAA onto the cathode surface, achieving removal and defluorination efficiencies of 99.66 % and 97.16 %, respectively (C₀ = 5 mg L⁻¹, applied voltage of −1.2 V vs. Ag/AgCl). Furthermore, the atomic H*, catalyzed by the Co−N₄ structure, boosts the reductive defluorination of TFMAA through indirect mechanisms, while the nitrogen loss due to carbonization further enhances the catalytic defluorination efficiency. This research presents a novel electrode material for PFASs defluorination and offers mechanistic insights into the defluorination process.