Modified MIL-100(Fe) for enhanced photocatalytic degradation of tetracycline under visible-light irradiation

Iron-based metal–organic frameworks (MOFs) with low cost and excellent photocatalytic potential are extremely attractive in the field of energy utilization and environmental remediation. In this study, a novel In2S3/MIL-100(Fe) photocatalyst was successfully synthesized by a facile solvothermal method for the first time. Several technologies (such as X-ray diffraction, scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy) were used to characterize the as-obtained samples and demonstrate the successful combination of MIL-100(Fe) and In2S3. Experimental results showed that 18% of tetracycline (TC) was adsorbed under dark condition and another 70% of TC was degraded under visible-light irradiation when treating 100 mL of TC solution (10 mg/L) with 30 mg of In2S3/MIL-100(Fe) composites. The corresponding TC removal efficiency was almost 1.9 and 1.6 times higher than that of pure MIL-100(Fe) and In2S3, respectively. The mechanism investigations revealed that the heterojunction composite exhibited superior charge transfer than either MIL-100(Fe) or In2S3, and this caused more efficient separation of electron-hole pairs. As a result, more radicals and holes were generated in the composite, leading to better photocatalytic performance. This work highlights the powerful combination of MOFs and semiconductor, which is a promising approach to fabricate heterojunction photocatalyst for wastewater purification.