Plasmon-Induced Degradation of Short-Chain PFAS by Noble Metal Nanoclusters

Per- and polyfluoroalkyl substances (PFAS) are widely used in industry and consumer products due to their unique physical and chemical properties. However, due to their toxicity and environmental persistence, the production of long-chain PFAS such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) has been systematically phased out. Instead, short-chain PFAS have been widely used as replacements for long-chain PFAS. However, recent studies indicate that even short-chain PFAS can be toxic to the environment. Despite numerous attempts, complete degradation of these short-chain PFAS has not yet been achieved, leaving room for further exploration. In this work, we explored the potential of plasmonic silver (Ag) and gold (Au) nanoclusters (NCs) in the complete degradation of short-chain PFAS. By considering icosahedral Ag₅₅ and Au₅₅ NCs, as well as different types of PFAS, we present a thorough study of plasmon-induced processes for NC-PFAS complexes. Among different decay channels, our study focuses on plasmon decay through the direct hot electron transfer (DHET) and direct hot hole transfer (DHHT) pathways from NC to PFAS. Our calculations reveal that DHET is more probable in Ag-PFAS complexes and DHHT is more probable in Au-PFAS complexes. Furthermore, among all complexes, the Ag-PFBS complex exhibits the highest DHET with a total probability of 10%. Our Ehrenfest molecular dynamics simulations show that the PFAS in Ag-PFAS complexes undergo efficient degradation in the presence of these hot carriers, albeit at different rates.