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

Abstract

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%.