Z-scheme heterojunction Bi2WO6/NH2-MIL-53(Fe) photocatalyst: Simultaneous efficient photo-Fenton degradation of SMX and photocatalytic reduction of Cr(VI)

The aim of this study was to develop a Z-scheme heterojunction Bi2WO6/NH2-MIL-53(Fe) photo-Fenton catalyst with enhanced electron-hole separation using an in situ growth method. Bi2WO6/NH2-MIL-53(Fe) promotes Fe(II)/Fe(III) cycling under visible light and trace H2O2 (5 μL) conditions, photo-Fenton degraded 82% of SMX within 60 min, 6.3 times that of pure Bi2WO6. It was also able to reduce Cr(VI) (20 mg/L) up to 97% efficiency under strong acidic conditions, which was 2.4 times that of Bi2WO6. In addition, Bi2WO6/NH2-MIL-53(Fe) has good stability and reusability, capable of degrading 75% of SMX and reducing 87% of Cr(VI) even after four cycles of testing. The mechanism of action of this catalyst was investigated by free radical trapping experiments, and the formation of Z-scheme heterojunction was demonstrated. In conclusion, Bi2WO6/NH2-MIL-53(Fe) is a promising photo-Fenton catalyst, which not only efficiently degrades antibiotics, but also exhibits excellent photocatalytic performance against Cr(VI) under strong acid conditions, providing a new idea for the treatment of complex pollutants.