Preparation and Properties of N-F Co-Doped TiO2 Photocatalyst with Wide Range Light Response and Multipore Structure from Ionic Liquid-Water Mixture Solvent

A yellow N-F co-doped TiO2 photocatalyst (TiONF) exhibited high activity over a wide light spectrum range and a multipore structure was prepared by a hydrolysis-precipitation method using an ionic liquid ([Bmim]PF6)-water mixture as the solvent and TiCl4 as the precursor. Photocatalytic activity was investigated by the photocatalytic degradation of phenol under ultraviolet (UV), artificial visible (Vis), and solar light irradiation. X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), spectroscopy, and N-2 adsorption-desorption were used for catalyst characterization. The results show that TiONF synthesis in an ionic liquid-water mixture solvent with suitable N-F doping gives high activity under UV, Vis, and solar light irradiation, and the activities are higher than those obtained by synthesis in pure water. The ionic liquid-water mixture solvent leads to N and F being incorporated into the TiO2 lattice and N-F co-doping can increase the amount of surface OH- on TiO2. The new bandgap formed by N-F doping can induce a second adsorption edge (450-530 nm), which can be excited by Vis irradiation and induceVis activity. N-F co-doping retards the phase transformation. In addition, an ionic liquid-water mixture as a solvent benefits the dispersion of TiO2, increases the S-BET and reduces the particle size.