Breaking the Forever Bonds: Interface-Enhanced Superoxide Chemistry for Efficient PFOA Degradation

The exceptional stability of carbon–fluorine (C–F) bonds in perfluorooctanoic acid (PFOA) presents a fundamental challenge in environmental remediation as traditional degradation methods struggle to break these bonds under mild conditions. Here, we demonstrate that the air–water interface in microdroplets can be strategically utilized to dramatically enhance PFOA (C0 = 20 mg L–1) degradation through a simple Fe(III)-Oxalate photochemical system, achieving complete destruction with 99% defluorination within 4 h at room temperature - a rate 2 orders of magnitude faster than conventional methods. Through comprehensive spectroscopic and computational investigations, we reveal that this remarkable enhancement stems from three synergistic interfacial effects: concentrated generation of superoxide radicals (O2·–) from earth-abundant Fe(III)-Oxalate complexes, significantly enhanced O2·- nucleophilicity due to disrupted solvation shells, and a strong interfacial electric field that catalyzes C–F bond activation. These molecular-level insights into interfacial chemistry not only provide an efficient and economical strategy for PFOA remediation but also establish a new paradigm for enhancing nucleophilic reactions in aqueous systems. Our findings highlight the transformative potential of air–water interfaces in activating traditionally inert chemical bonds, offering new opportunities for both environmental protection and chemical synthesis.