TiO2/quasi-MOF UiO-66 and Fe2O3/Quasi-MOF UiO-66 nanocomposites for photocatalytic removal of methylene blue

Abstract

This study reports the synthesis and characterization of TiO2/Quasi-MOF UiO-66 and Fe2O3/Quasi-MOF UiO-66 nanocomposites as effective photocatalysts for the removal of cationic dyes, with a focus on methylene blue (MB). The nanocomposites were synthesized via a sonochemical method, with precise control over precursor types and molar ratios to optimize their morphology, particle size and surface properties. A series of analytical techniques, including X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier- Transform Infrared Spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) surface area analysis and diffuse reflectance spectroscopy (DRS) were employed to characterize the morphology, phase purity and optical properties of the synthesized materials. BET analysis revealed specific surface areas of 998.2 m2.g-1 for TiO2/Quasi- MOF UiO-66 and ~850 m2.g-1 for Fe2O3/Quasi-MOF UiO-66. DRS data and Tauc plot analysis indicated a bandgap energy of approximately 3.1 eV for the TiO2/Quasi-MOF UiO-66 composite, situating the TiO2-based material within the UV light activation range and supporting its potential for MB, with removal rates reaching up to 93.58%. Mechanistic studies indicated that hydroxyl radicals (HO•) generated under UV light irradiation play a vital role in the decomposition of dye molecules. Kinetic analysis using the Langmuir–Hinshelwood model revealed a reaction rate constant of 0.67 min???? 1 for the optimal conditions, underscoring the potential of these MOF-based composites for environmental remediation applications. The superior activity of the TiO2/Quasi-MOF UiO-66 composite relative to its individual components is consistent with a cooperative interaction between the metal oxide and the UiO-66 framework.