Hydrothermal synthesis and evaluation of visible-light-active photocatalyst of (N, F)-codoped anatase TiO2 from an F-containing titanium chemical

A visible light active TiO2 photocatalyst was synthesized hydrothermally from an aqueous solution containing (NH4)2TiF6 and NH3 at 140 or 160°C. The prepared samples were characterized with X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and UV-Vis diffuse reflectance spectroscopy. The prepared samples showed obvious absorption in the wavelength range of 400-550 nm with a red shift in the adsorption edge. It was found that the prepared samples exhibited photocatalytic activity on degradation of methylene blue (MB) in water under visible light. The ion-doped TiO2 obtained by hydrothermal treatment at 160°C for 7 d had the highest photocatalytic activity. The formation of Ti-N and Ti-F bonds was confirmed by X-ray photoelectron spectroscopy (XPS).