Fabrication of Fe3O4 quantum dots modified BiOCl/BiVO4 p-n heterojunction to enhance photocatalytic activity for removing broad-spectrum antibiotics under visible light

Herein, Fe 3 O 4 quantum dots modified BiOCl/BiVO 4 p-n heterojunction was successfully synthesized by a facile strategy. Multiple techniques were carried out to characterize the as-prepared samples. Results show that the photocatalysts possess regular crystal structure and consisted of BiOCl/BiVO 4 nanosheet structure with Fe 3 O 4 QDs on its surface. Particularly, 20% Fe 3 O 4 QDs@BiOCl/BiVO 4 p-n heterojunction shows universal outstanding photocatalytic activity for removing four different broad-spectrum antibiotics under visible light. Meanwhile, the mineralization degree and degradation pathways of antibiotic were further studied by 3D-EEMs and LC-MS/MS. The improved photocatalytic performance for degradation of broad-spectrum antibiotics mainly attributes to the effective charge carrier mobility, large specific surface areas, and strong visible light absorption. The photocatalytic reaction mechanism was also revealed by the electron spin resonance (ESR) technique and the active species trapping experiments. The photocatalyst stays stable crystal structures after four reaction cycles and it can be easily separated from the solution by an external magnetic field both demonstrate that the Fe 3 O 4 QDs@BiOCl/BiVO 4 p-n heterojunction has unlimited potential for practical usage. This work is expected to be widely applicable to the removal of broad-spectrum antibiotics.