Electrocatalytic polyvinylidene fluoride defluorination with water mediation at room temperature.

Polyvinylidene fluoride (PVDF), a widely used recalcitrant per- and polyfluoroalkyl substance (PFAS) polymer, poses environmental challenges in its defluorination because conventional thermal methods release toxic volatile fluorinated compounds (VFCs). Here, we report an electrochemical water-mediated strategy for efficient, VFC-free PVDF defluorination under ambient conditions. The method achieves a high fluorine-to-fluoride conversion (93%) and is validated with an industrially relevant capacity of 8.5 kg·m-3·day-1 on real wasted battery electrodes containing PVDF as the binder. The high efficiency originates from the spatial confinement of electrochemically generated hydroxide ions near the cathode surface. Mechanistically, isotopic labeling and kinetic Monte Carlo simulations reveal water's unprecedented dual role as both a reactant and a catalyst, driving an ionic pathway that fundamentally suppresses VFCs. This offers a scalable, sustainable, and nontoxic alternative for the critical challenge of C─F breaking and PFAS defluorination.