Trap-n-zap: Electrocatalytic Degradation of Perfluorooctanoic Acid (PFOA) with UiO-66 Modified Boron Nitride Electrodes at Environmentally Relevant Concentrations

Poly- and per-fluoroalkyl substances (PFAS) are synthetic chemicals of increasing global concern due to their toxicity and environmental persistence. Hexagonal boron nitride (h-BN) is an electrochemically active semiconductor that generates a hydrophobic electron-hole with a high affinity for the fluorinated tail of perfluorooctanoic acid (PFOA), which enhances surface interactions in aqueous solutions. We demonstrate that h-BN electrocatalytically oxidizes PFOA to shorter chains. The degradation is enhanced by modifying the h-BN surface with an adsorbent, UiO-66 (UiO-66@BN), that facilitates proximal adsorption to catalytic sites (trap-and-zap). At the environmentally relevant concentration of 100µg/L, electrochemical trap-and-zap removes 99.5% of PFOA with 70% defluorination in 3hours at a pH 4.5. Computational results show that PFOA requires an overpotential of 1.87V vs. SCE, which is close to the experimental overpotential. The electrical energy per order (EE/O) of UiO-66@BN is 6.1 kWh/m3, indicating that it is a competitive material for PFOA electrochemical remediation.