Self-cleaning ceramic tiles coated with Nb2O5-doped-TiO2 nanoparticles

In this work, 5 mol% Nb2O5-doped TiO2 synthesized sol was sprayed on glazed ceramic tiles. The crystallization of TiO2 nanoparticles occurs on the surface of the tiles after annealing at 600-900 degrees C, this innovative approach leads to a drastic decrease in the titania grain size as detected by SEM and XRD. The superhydrophilic and self-cleaning performance was evaluated by measuring the water contact angle under UV irradiation and by degradation of methylene blue according to ISO 10678 and JIS R1703-2. The results showed a high performance of doped samples at all temperatures tested, with a marked dependence on the anatase-to-rutile ratio and crystallite size. At 800 degrees C, the doped samples achieved water contact angle near to zero in just 15 min of UV irradiation, which confirms the high performance of the self-cleaning ceramic tiles.