Surface Fluorination Engineering of FeCo Prussian Blue Analogs with Boosted Peroxidase-Like Activity and Selectivity: An Integrated Nanozyme-Membrane Sensing Platform for Perfluorooctanesulfonate

Accurate and sensitive analysis of perfluorooctanesulfonate (PFOS) is essential for environmental pollution traceability and risk assessment. Herein, a surface fluorination engineering strategy was proposed to construct fluorinated FeCo Prussian blue analogs (FeCo-PBA-F) nanozyme with boosted peroxidase-like activity and high selectivity. The porous hollow structure and fluorine-induced electron deficiency of metal centers endowed FeCo-PBA-F with superior enzymatic performance over horseradish peroxidase. Moreover, the fluorine-rich surface enabled highly selective binding of PFOS via the fluorine-fluorine interaction. A colorimetric sensing mechanism was established based on the inhibition of peroxidase-like activity caused by competitive binding and altered oxidation states of Fe/Co. To achieve rapid and on-site detection of PFOS, a nanozyme-membrane sensing platform was constructed by integrating FeCo-PBA-F nanozyme and fiber membranes, performing a highly sensitive and selective analysis of PFOS with a detection limit of 4.3 nM within 5 min. As a case study, the platform was applied to surface water, industrial wastewater, and printing and dyeing wastewater samples, which showed satisfactory consistency compared with the fluorescence method, indicating excellent practicality and reliability in real applications. This work introduces a practical surface fluorination engineering strategy to enhance enzyme-like activity and selectivity and provides a practical tool for PFOS detection in environmental water samples.