Anatase TiO₂ co-doped with silver and silica for destruction of organic dye and bacteria

The purpose of this study was to apply a peroxo sol–gel method to prepare silver and silica co-doped TiO₂ to enhance the stability of sol, TiO₂ particle size distribution, and improve photocatalytic activity under UV light or visible light irradiation. TiO₂ sol was prepared by peroxo sol–gel method using TiCl₄ as precursor and H₂O₂ as peptizing agent in order to induce the formation of TiO₂ nanoparticles that converted from Ti(OH)₄ at 95 °C. Silver and SiO₂ were then added in the TiO₂ sol to improve the photocatalytic activity and the transmittance of the sol. The Ag/TiO₂–SiO₂ nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscope, X-ray photoelectron spectroscopy, dynamic light scattering, and UV–Vis spectroscopy. The sols remained neutral, stable, and did not precipitate after storage for over a year. TiO₂ was anatase as confirmed by XRD. Ag/TiO₂–SiO₂ films were active for destruction of methylene blue under UV light and visible light irradiation. The optimum Ag/SiO₂/TiO₂ molar ratio was 0.02/5/1. It showed the highest photocatalytic activities under both of UV light and visible light irradiation among all catalysts. The antibacteria test showed that after irradiation by UVA light for 3 h, the Ag/TiO₂–SiO₂ had a high antibacteria ability, and the antibacteria rate reached over 99.9%. [Figure not available: see fulltext.]