Superior Water Sheeting Effect on Photocatalytic Titania Nanowire Coated Glass

Simple, rapid, and inexpensive fabrication of self-cleaning glass surfaces based on wet chemical deposition of H₂Ti₃O₇ (trititanate) and subsequent transformation of it into TiO₂ (anatase) nanowires on pristine glass surfaces is reported. Despite the low, 55%, surface coverage, the nanowire roughened glass surface showed self-cleaning properties comparable to much thicker, over 100-nm-thick, TiO₂ nanoparticle coated glasses. The superwettable surface showed 12° contact angle. Moreover, ultraviolet (UV) and natural light activated photocatalysis remained effective at enhancing the self-cleaning process in the case of the TiO₂ nanowire coated glass. Time-resolved study of the water droplet spread in millisecond time scales revealed that capillary forces induced by the random nanowire network significantly enhance the water sheeting effect of these textured glass surfaces. Time-resolved experiments revealed that the spreading velocity of the droplets were enhanced by 19% for the TiO₂ nanowire roughened surface and reached a v₀ = 508 mm/s initial spreading speed. Outdoor experiments validated the concept that TiO₂ nanowire coated glass possess self-cleaning properties with significantly reduced titania content compared to nanoparticle based films.