Effect of the addition of different doping agents on visible light activity of It porous TiO2 photocatalysts

The influence of the addition of different doping agents (N, W and Hf) on the macroporous TiO2 photoactivity toward the Rhodamine B degradation and ethanol photo-oxidation was evaluated. The samples were characterized by XRD, XPS, SEM, TEM, N-2 adsorption-desorption, UV vis Diffuse Reflectance and Photoluminescence spectroscopies to study also the changes in the physico-chemical properties due to the presence of dopants. The photonic effect and the high ordered porous structure of the macroporous TiO2 that lead to increase the path length of the light, were the key factors that allow to enhance the catalytic activity towards the dye and VOC degradation under visible and solar light irradiation of these materials compared to the commercial TiO2 anatase. A significant improvement of the catalytic performances was achieved when the amount of the dopant was low, the ionic exchange of TO4+ ions by doping ions and the consequent substitution in the crystal lattice of TiO2 was favoured, and/or the formation of non-stoichiometric Ti-compound on the TiO2 surface was promoted.