Synthesis of C/N-TiO2@MIL-100(Fe) for highly efficient photocatalytic degradation of tetracycline under visible light irradiation

Carbon and nitrogen-doped titanium dioxide (C/N-TiO2) and metal–organic frameworks (MOFs) of MIL-100(Fe) were synthesized by the hydrothermal method. C/N-TiO2@MIL-100(Fe) (M/CNT-x) composites were successfully created by hydrothermally compounding MIL-100(Fe) onto the surface of C/N-TiO2. The photocatalytic activity of the samples was assessed based on the degradation of tetracycline under visible-light irradiation. M/CNT composites with different MIL-100(Fe) contents were prepared by hydrothermal method. SEM, TGA, XRD, FT-IR, XPS, BET, UV–vis-DRS, and PL studies were used to describe the shape and structure of the samples. The composite C/N-TiO2@MIL-100(Fe) with 10 % MIL-100(Fe) content exhibited the best structural stability and photocatalytic activity. Under 120 min of visible light irradiation, the breakdown rate of tetracycline reached 98.7 %. Furthermore, after four cycles, the degradation rate can still reach 89.9 %. The incorporation of non-metallic components and MIL-100(Fe) resulted in a notable reduction in the band gap of TiO2 and an expansion of its visible light absorption, which in turn enhanced the composites' photocatalytic activity. Meanwhile, it results from the composites' interfacial synergy, which efficiently encourages the transfer of electron-hole pairs. These results imply that the C/N-TiO2@MIL-100(Fe) composite is a stable and effective catalyst for tetracycline breakdown in industrial effluent.