Fabrication of TiO2/MoS2 Composite Photocatalyst and Its Photocatalytic Mechanism for Degradation of Methyl Orange under Visible Light

A novel TiO2/MoS2 composite photocatalyst with high visible-light activity was prepared via a one-step hydrothermal process using titaniumtetrachloride (TiCl4) as a titanium resource and bulk MoS2 as a direct photosensitizer. The photocatalytic degradation of methyl orange (MO) in aqueous suspension was employed to evaluate the visible light activity of the as-prepared composite photocatalyst with a xenon lamp as simulated solar irradiation. The chemical composition, optical properties, morphology, structure, and thermal stability of the composite photocatalysts were characterized using XPS, UV-vis, FS, SEM, XRD, and TGA. The as-prepared photocatalysts exhibited enhanced photocatalytic activity from the experiment on the degradation of methyl orange, compared to the performance of commercial titania (Degussa P25). The degradation rate of MO can reach over 90% in 10min when the molar ratio of molybdenum disulfide (MoS2) to titanium dioxide (TiO2) is 0.8:50 and the mass concentration of the TiO2/MoS2 composite photocatalyst is 400mg/L. In this research, a new fabrication mode of TiO2/MoS2/TiO2 was applied for fabricating new hybridized structures of nano-TiO2/MoS2 by using bulk MoS2 as a direct photosensitizer, which changed the energy levels of the conduction band of MoS2 and strongly promoted interparticle electron transfer. In addition, this hybridization structure was believed to have a synergistic effect in the process of photocatalytic oxidation owing to increasing the degree of charge carrier separation, which effectively reduced recombination and improved the photocatalytic activity of the TiO2/MoS2 composite photocatalyst.