Construction of double Z-scheme Ag3PO4/MOF-In2S3/Bi2S3 heterojunction by micro-Ag bridges for photocatalytic degradation of levofloxacin

Designing heterogeneous photocatalysts to enhance the activity of photo-induced ch arge separation for efficient degradation of organic pollutants in aqueous systems remains a significant challenge. A double Z-scheme Ag3PO4/MOF-In2S3/Bi2S3 heterojunction containing trace Ag compositing was rationally designed and prepared, and fully characterized. Nitrogen adsorption–desorption experiments and Ultraviolet–Visible diffuse reflection spectroscopy (UV–Vis DRS) showed that the heterostructure expanded the surface area of single component, and had the highest absorption rate and the widest range of light. The presence of Ag in this heterostructure was demonstrated by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS), which explained the strong resistance to photo corrosion and the highest current density exhibited by the composite in photocurrent response testing. The photocatalytic degradation of the antibiotic levofloxacin (LVX) was carried out, in which the degradation proportion of ABIS-Ⅲ sample was as high as 93.6 % within 90 min. Free radical scavenging assay and ESR experiment demonstrated that OH and O2– worked together to promote the degradation of LVX. Combined theoretical calculations with experimental results to reasonably construct a double Z-scheme to elaborate the carrier migration paths under light illumination. This novel double Z-scheme model heterojunction is expected to provide new ideas for the study of the photocatalytic mechanism of multiplicity complexes and the removal of antibiotic contaminants.