NH2-MIL-101(Fe)/WO3 heterojunction composite PVDF photocatalytic membrane for highly efficient dye degradation under visible light

In this study, NH2-MIL-101(Fe)/WO3 heterojunctions were prepared by solvothermal method and then incorporated into polyvinylidene fluoride (PVDF) membranes via phase inversion method to fabricate recyclable photocatalytic membranes with high degradation performance. The SEM and XRD characterization results indicated that NH2-MIL-101(Fe) and WO3 were physically combined. Using MB as the target pollutant, the membrane with 30 mg of Tungsten trioxide（WO 3 ） doping exhibited optimal degradation performance, achieving complete MB degradation within 100 min and a TOC removal rate of 85 %. During the degradation process, superoxide radicals (·O 2 − ), hydroxyl radicals (·OH) and photogenerated holes (h⁺), played a major role. The results of UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence (PL) spectra showed that the incorporation of WO 3 effectively suppressed the recombination of electron-hole pairs and enhanced visible light absorption, thereby improving the photocatalytic activity. Transient photocurrent response (i-t) and electrochemical impedance spectroscopy (EIS) tests further demonstrated that the composite photocatalyst with 30 mg of WO 3 exhibited the highest photocurrent density and the lowest charge transfer resistance. Degradation cycling experiments revealed that after four cycles of degradation, the PVDF photocatalytic membrane maintained high photocatalytic activity for MB. This study suggests that the combination of NH 2 -MIL-101(Fe)/WO 3 and PVDF membranes provides a promising new approach for exploring wastewater treatment solutions.