Synthesis, characterization and photocatalytic activity of Li-, Cd-, and La-doped TiO2

The doping of TiO2 powder was done by a substance containing lithium, cadmium and lanthanum through the sol-gel process in order to widen their absorption in the visible light range. This mixture is subsequently calcined at 450 °C. Measurements of UV-vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), scanning electron microscope (SEM), specific surface area and porosity show that, at this temperature, TiO2 which is doped with Li, Cd and La is formed with a response in the visible light range. The evaluation of the photocatalytic activity was carried out using 4-nitrophenol as a model of chemical pollutants in UV and visible conditions. The adsorption isotherms of doped TiO2 follow the Langmuir model and photodegradation shows the Langmuir Hinshelwood model-regardless of TiO2 morphologies. TiO2 doped with lithium (5%) has a photocatalytic activity five times higher than the TiO2 P25 in the visible light range and it also helps to achieve complete mineralization of 4-NP within a short irradiation time. This sample is attributed to the smallest surface and is of anatase crystallites.