Catalytic reactive-hydrogen membranes for rapid capture and hydrodefluorination of six PFAS of regulatory concern

Per- and polyfluoroalkyl substances (PFAS) persist in aquatic environments due to their ultrastable C–F bonds and poor susceptibility to conventional treatment. Here, we report an H 2 -based catalytic-film membrane that enables PFAS destruction in ambient conditions by generating highly reactive surface (H ads * ) and subsurface hydrogen (H sub * ), the latter stored as β-phase palladium hydride (β-PdHx). Solid-state analyses evidenced β-PdHx formation and related lattice expansion with elevated H 2 chemical potential, revealing a structural mechanism that links hydrogen storage to catalytic defluorination. Mechanistically, the two hydrogen species play complementary roles: H ads * -rich Pd 0 surface enabled PFAS capture through parallel adsorption to maximize interfacial contact with active H, whereas sustained H sub * supplied the energetic driving force for stepwise hydrodefluorination consistent with sequential C–F scission. As a result, across six PFAS of regulatory concern—PFOA, PFOS, PFNA, PFHxS, PFBS, and GenX—the catalytic membrane converted all contaminants toward fully defluorinated products. Long-chain PFAS were removed and defluorinated more rapidly than short-chain analogs, while GenX showed greater recalcitrance due to its ether linkage, weaker adsorption, and higher average C–F bond dissociation energy; nonetheless, GenX still exhibited removal and defluorination, with the production of 2-propoxypropanoic acid. The system also enabled continuous coremoval of all six PFAS in ambient conditions, with up to 96% removal and 83% defluorination over 58 d. These findings provide a mechanistic framework for how active hydrogen is generated, stored, and deployed in catalytic membranes, and identify engineered H 2 -catalytic membranes as a promising low-energy technology for destructive PFAS treatment.