摘要

Developing heterogeneous catalysts with high level of active site exposure is crucial for the activation of peroxymonosulfate. In this study, a series of high-performance Fe-N-C catalysts were obtained through the strategy of melamine-assisted pyrolysis. The morphology, specific surface area and pore structure of the catalysts can be adjusted by controlling the amount of melamine added during the pyrolysis process. Fe-1-Nx-C obtained with a melamine to Fe-ZIF ratio of 1:1 exhibited the highest specific surface area (984.2 m(2)<middle dot>g(-1)), pore volume (1.79 cm(3)<middle dot>g(-1)) and reaction rate constant (0.055 min(-1), 5.5 times that of Fe-0-Nx-C). Furthermore, Fe-1-Nx-C showed high stability and reusability in multiple cycles, maintaining high catalytic activity with pH range of 3-9. The addition of melamine can cause selective cleavage of C-N bonds, converting the central Fe-Nx sites into more active edge-defective Fe-Nx sites, thereby enhancing the catalytic activity. Quenching experiments and electron paramagnetic resonance (EPR) detection confirmed the dominance of O-1(2) in the degradation of Bisphenol AF (BPAF). Two possible pathways for BPAF degradation were proposed based on liquid chromatography-mass spectrometry (LC-MS) and density functional theory (DFT) calculations. This study provides a new way to design and construct Fe-N-C catalysts with ideal pore structures, and enhance the accessibility of active sites inside the catalysts.

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