Dye-Sensitized\nCommercial TiO<sub>2</sub> for the\nConstruction of Robust Nanocoatings with the Enhanced Transmittance\nand Visible-Light-Activated Photocatalytic Self-Cleaning Properties

TiO<sub>2</sub>-based nanocoatings exhibit great promise\nin practical\napplications owing to their superior photocatalytic property. However,\nbecause of the wide band gap of TiO<sub>2</sub>, its photocatalytic\ncapacity is only limited in the ultraviolet range. Herein, we designed\nand constructed robust SiO<sub>2</sub>@TiO<sub>2</sub> composite nanocoatings\nwith improved transmittance and visible-light-activated photocatalytic\nself-cleaning properties. Sulfonated cobalt(II) phthalocyanine (CoPcTs)\nwas used as an organic dye to sensitize commercial TiO<sub>2</sub> nanoparticles (Degussa P25) to form CoPcTs-P25 for visible-light\nphotocatalysis. CoPcTs-P25 and small-sized solid silica nanoparticles\n(SSNs) were utilized as two building blocks, and acid-catalyzed silica\nsol (ACSS) was used as a binder to fabricate the nanocoatings via\na simple dip-coating method without requiring any post-processing.\nBy tuning the mass ratios of SSNs to CoPcTs-P25, the nanocoating with\nthe optimized property showed the highest transmittance of ca. 97.0%\nat the wavelength of 566 nm, higher photocatalytic activity of degrading\nthe organic pollutants than N–TiO<sub>2</sub>-based nanocoatings,\nhigh mechanical firmness of 3H level in pencil hardness test and 4A\nlevel in tape adhesion test, and good weather resistance. In short,\nthe dye-sensitized commercial P25 TiO<sub>2</sub> nanoparticles should\nbe a promising building block for low-cost and easy preparation of\nrobust nanocoatings with enhanced transmittance and visible-light-activated\nphotocatalytic self-cleaning properties.