Continuous synthesis of a co-doped TiO₂ photocatalyst and its enhanced visible light catalytic activity using a photocatalysis microreactor

Three kinds of co-doped TiO₂ nanomaterials were synthesized by using a continuous precipitation method with a valve assisted micromixer in the presence of additives and titanate sources. The research results revealed that co-doped elements were incorporated into the lattice of TiO₂ by substituting Ti and O atoms in the lattice of TiO₂. Compared with conventional methods, the substitution process was realized within a few seconds. The resulting nanoparticles were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nitrophysisorption measurements, X-ray photoelectron spectroscopy (XPS) and diffused reflectance UV-visible spectra (DRS). The synthesized samples were evaluated in the degradation of methyl orange dye (MO) under UV and visible light irradiation at room temperature. Fe, S co-doped TiO₂ (TiO₂-Fe-S) showed nearly the same catalytic efficiency compared with pure TiO₂ (5-10 nm) under UV irradiation. The visible photocatalytic activity was higher than pure TiO₂ (5-10 nm) under visible light irradiation.