Preparation and characterization of Cu-doped TiO2 nanomaterials with anatase/rutile/brookite triphasic structure and their photocatalytic activity

Pure TiO₂ and Cu–doped TiO₂ containing different amounts of copper ions with anatase/rutile/brookite triphasic structure were successfully synthesized through a simple hydrothermal method. The obtained samples were characterized by X–ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), X–ray photoelectron spectroscopy (XPS), UV?vis diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL) and Brunauer–Emmett–Teller surface area analyze (BET). Both pure and Cu–doped TiO₂ show relatively high photocatalytic activity owing to their considerable surface areas. Moreover, the three–phase coexisting structure and the conversion between Cu²⁺ and Cu⁺ ions facilitate the separation of photogenerated electrons and holes, which is favorable for photocatalytic performance. 1%Cu–TiO₂ exhibits the highest photocatalytic activity and the degradation degree of rhodamine B (RhB) reaches 93.5% after 30 min, which is higher than that of monophasic/biphasic 1%Cu–TiO₂. ·O₂^? radical is the main active species, and h⁺ and ·OH species are subsidiary in the degradation process.