Heterogeneous PFAS Defluorination and Fluoride Upcycling into Medicinal Agents in Aqueous Electrolytes

Per- and polyfluoroalkyl substances (PFASs) mineralization and the upcycling of released fluoride (F^-) are desired for closing the fluorine cycle. While PFAS filtration and degradation are ongoing research, comprehensive PFAS mineralization followed by immediate valorization of the released F^- remains rare. Herein, we report a heterogenized copper-(I) electrocatalyst that fully (100%) decomposes 0.5 mM perfluorooctanoic acid (PFOA), a common groundwater PFAS contaminant, in aqueous KHCO₃ electrolyte at an anodic current of 5 mA over 18 h. Up to 84% PFOA degradation was achieved at the maximum tested concentration (2 mM) under identical electrochemical conditions, along with a corresponding 91% F^- recovery rate. Interestingly, KHCO₃ acts beyond a supporting electrolyte, influencing the rate-limiting step involved in PFOA defluorination, as revealed by the detection of ¹³CO₂H-incorporated PFOA under ¹³CO₂. In addition, we examined the degradation and defluorination rates of 11 PFASs with different chain lengths and configurations, and also valorized the produced F^- for the in-situ syntheses of medicinally relevant alkyl/arylsulfonyl fluorides (R-SO₂F, R = -Me, -(CH₂)₂Cl, and benzyl), without extracting F^- from the post-electrolysis solution and applying current/potential during the fluorination event. This report showcases a rare heterogenized molecular Cu-(I)-electrocatalyst for mineralizing PFASs and the subsequent room temperature F^- valorization.