Plasmon-enhanced reductive defluorination of PFAS in water under ambient conditions.

Photo-driven, plasmon-enhanced catalysis enables polyfluoroalkyl and perfluoroalkyl substance (PFAS) degradation in water under ambient conditions. Here we show that ultraviolet (UV) irradiation-induced localized surface plasmon resonance drives reductive defluorination of perfluorooctanoic acid and perfluorooctane sulfonic acid, two legacy contaminants. Stable, quantum-sized palladium and platinum nanocatalysts supported on aminated mesoporous silica nanoparticles (MSN-NH2-Pd and MSN-NH2-Pt) transform perfluorooctanoic acid and perfluorooctane sulfonic acid with stoichiometric, or near-stoichiometric, fluoride release under low-intensity UVC or UVA irradiation at room temperature. Time-resolved 19F nuclear magnetic resonance, high-resolution mass spectrometry and complementary analyses indicate a stepwise reductive hydrodefluorination pathway in which oxidized, short-chain products do not measurably accumulate under the conditions studied. Scavenger and control experiments are consistent with hydrated electrons and in situ hydrogen generation as key reactive species. Taken together, the results indicate that synergistic interfacial PFAS sorption, plasmon-induced hydrogen evolution and hydrated electron formation drive PFAS defluorination under mild reaction conditions.