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Titanium dioxide (TiO 2 ) thin films were rapidly coated on Corning glass substrates from the precursor solution using the wire-bar technique at the room temperature and then post-annealed at 400, 500 and 600 • C for 1 h under atmospheric conditions. The structural, morphological, optical, wettability and photocatalytic properties of the films were studied. X-ray diffraction analysis confirmed the formation of an anatase TiO 2 structure irrespective of the post-annealing temperatures. The optical transparency of the films in the visible range was measured to be > 70%. A water contact angle (WCA) of~0 • was observed for TiO 2 thin-film, post-annealed at 400 • C and 500 • C. However, WCA of 40.3 • was observed for post-annealed at 600 • C. The photocatalytic dye-degradation using post-annealed thin-film was investigated indicating a steady improvement in the dye-degradation percentage (from 24.3 to 29.4%) with the increase of post-annealing temperature. The demonstrated TiO 2 thin-films deposited by wire-bar coating technique showed promises for the manufacturing of large-area cost-effective self-cleaning window glass.Molecules 2020, 25, 1683 2 of 13 sheeting water and the later by rolling water droplets that carries away dirt [8]. The superhydrophilic and superhydrophobic properties are attractive in self-cleaning applications and are commonly evaluated based on the water contact angles (WCAs) with the material/surface. WCAs of <5 • and >150 • are called superhydrophilic and superhydrophobic materials respectively [8]. The superhydrophilic material when employed on a substrate/surface leads to the formation of uniform thin layer of water upon contact and gradually carries away dust particles from the surface [9]. In contrast, hydrophobic surfaces accumulate small water droplets, leading to deterioration of transparency [7,9]. In the current context, TiO 2 thin layers are capable of photocatalytically degrading the organic pollutants present on glass and tiles and irregular shapes on solid surfaces when irradiated with UV light or sun light [8,9]. The decomposed organic pollutant or dirt can be washed away by sheeting water without the need of additional mechanical cleaning due to its superhydrophilic nature [7,8]. Recently, the scope of superhydrophilic and photocatalytic TiO 2 thin-films has been widened to air purification for the effective decomposition (and the subsequent removal) of nitrogen oxide (NO x ), formaldehyde, benzene and other volatile organic compounds (VOCs) [10][11][12]. The air purification processes convert toxic gases to harmless compounds like nitrate ions that are ultimately washed into the soil and help to fertilize plants [10]. The unique wettability and non-toxic properties of TiO 2 materials are also employed in biomedical applications where surface wettability can play an important role in protein adsorption, cell adhesion and proliferation [9]. Moreover, the antibacterial, self-cleaning, and anti-odour properties of TiO 2 films deposited on fibres, textile, cotton, etc. also allow thi...

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