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 °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 °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.