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.