Sunlight-activated composite TiO2-F-V-Mo materials for photodegradation of the organic pollutant methylene blue

Abstract

F-doped TiO2 photocatalyst materials were prepared using solid-state and sol-gel synthesis with varying weight percentages of LiF or NH4F. Subsequently, molybdate and vanadium oxide were added to the prepared powders to create composite photocatalysts with reduced bandgap energy, enhancing light absorption in the visible region of the spectrum, which is essential for effective photocatalytic activity using sunlight. The synthesized powders were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and specific surface area using the BET method. The crystallization and anatase-to-rutile phase transformation of the powders were verified by X-ray diffraction (XRD), and the composite nanoparticles were further investigated by transmission electron microscopy (TEM). The photocatalytic activity of the F-doped commercial TiO2, sol-gel synthesized TiO2, and prepared composite powders was evaluated through the photocatalytic degradation of methylene blue (MB) in water under ultraviolet (UV), UV–visible, and sunlight irradiation. The results indicated that the incorporation of Molybdenum and Vanadium significantly influenced the photocatalytic efficiency by substantially reducing the bandgap of this composite photocatalyst. The LiF-doped TiO2 powders synthesized by sol-gel using TTIP, and doped with vanadium and molybdenum, activated by sunlight, exhibited high performance in MB degradation compared to commercial TiO2 and undoped synthesized TiO2 powders, achieving an optimal degradation rate of 7.26 × 10⁻⁹ mol per gram of photocatalyst.