Solvothermal construction of MIL-101(Fe)/Bi₂S₃ Z-scheme heterojunctions: performance in photo-fenton degradation of antibiotics and dyes

A novel MIL-101(Fe)/Bi₂S₃ Z-scheme heterojunction with a metal–organic framework (MOF) structure was synthesized via a solvothermal method. Compared with pristine MIL-101(Fe) and pristine Bi₂S₃, this composite exhibits a significant breakthrough in degradation performance toward rhodamine B (RhB) and tetracycline hydrochloride (TCH). Specifically, it achieves a degradation efficiency of 95.7% for 20 mg/L TCH within 120 min and 98.6% for 40 mg/L RhB within 90 min.Characterizations including X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and electrochemical impedance spectroscopy (EIS) confirm that the MOF structure of MIL-101(Fe) provides a stable support matrix for Bi₂S₃. Moreover, the construction of the Z-scheme heterojunction can effectively suppress the recombination of photogenerated electron–hole pairs while retaining the strongly oxidizing hydroxyl radicals (・OH) and strongly reducing superoxide radicals (・O₂⁻). More importantly, after five recycling cycles, the degradation efficiencies of the composite for TCH and RhB remain at 86.8% and 88.6%, respectively, with no obvious damage to its crystal structure after cycling. This demonstrates superior structural stability and reusability compared to most reported MOF-based photo-Fenton catalysts.