Degradation of metronidazole by Bi3O4Br/MIL–88B(Fe) Z–scheme heterojunction: Performance and mechanisms

This study reports the synthesis of MIL–88B(Fe)/Bi 3 O 4 Br, an efficient Z -scheme heterojunction photocatalyst for metronidazole (MNZ) degradation. The composite achieved a degradation efficiency of 95.2 % under visible light irradiation, outperforming the single-component catalysts (MIL–88B(Fe): 39.0 %, Bi 3 O 4 Br: 71.5 %). Photocatalytic treatment reduced biotoxicity, indicating its potential for use and environmental safety. The degradation process of MNZ was revealed by integrating LC–MS data with Fukui function analysis. Photoelectrochemical findings indicate that MIL–88B(Fe) enhanced efficiency, facilitated charge separation, and augmented the spectral response of Bi 3 O 4 Br. The Z–Scheme charge transfer and the function of the built–in electric field were validated by in situ XPS. DFT calculations revealed synergistic effects in the composite system, enhancing the adsorption and photocatalytic properties for MNZ. This study proposed a thorough degradation process that underpinned the development of effective photocatalysts.