A ternary metal-free porous carbon nitride-polypyrrole-montmorillonite (CN-PPy-MMt) nanocomposite photocatalyst was fabricated via an <i>in situ</i> method. To the best of the author’s knowledge, this is the first report of this <i>in situ</i> synthetic approach, and the application of the resulting photocatalyst was verified for the degradation of metronidazole (MZ) under visible light irradiation. The mixing rate of montmorillonite was optimized to 10% by the above application. This superior photocatalytic degradation performance was attributed to the synergistic inter-constituent interactions within the CN-PPy-MMt nanocomposite, which effectively facilitated the separation and channelization of photo-generated electron-hole pairs. The results were confirmed by higher photocurrent intensity, lower impedance resistance, and lower photoluminescence intensity of CN-PPy-MMt nanocomposite. Moreover, the radical scavenger tests indicate that superoxide radicals and holes play major roles in the mineralization of MZ, and the intermediate products were identified to be 1-(2-hydroxyethyl)-2-methyl-5-aminoimidazole, 2-methyl-5-nitroimidazole, and 1-(2-hydroxyethyl)-2-methyl-5-imidazole by LC-MS. The photocatalytic degradation mechanism of MZ was proposed. Finally, the reusability and stability of the photocatalyst were also evaluated. These findings provide new insights for the design of analogical metal-free photocatalysts in antibiotic degradation and beyond.

Metal-free porous carbon nitride-polypyrrole-montmorillonite nanocomposite for photocatalytic mineralization of metronidazole

ACS Spring Meeting 2021

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