Facile synthesis and kinetic mechanism of Ag-doped TiO 2 /SiO 2 nanoparticles for phenol degradation under visible light irradiation

Ternary Ag–TiO2–SiO2 nanocomposite photocatalysts were synthesized via a facile sol–gel method and characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscope, X-ray photoelectron spectroscopy, surface area analyzer (BET method) and UV-diffuse reflectance spectroscope, respectively. The results indicated that the crystallite size of TiO2 reduced after being doped by SiO2 and Ag, while the agglomeration and phase transition of TiO2 nanoparticles were restrained, resulting in the greatly increased specific surface area of Ag–TiO2–SiO2. Moreover, the adsorption edge of TiO2 obviously red-shifted from UV to visible light range, indicating the higher utilization of solar energy. The photocatalytic performance was evaluated by the degradation of phenol under visible light (λ > 420 nm) irradiation. The degradation rate of phenol over 1%Ag–TiO2–SiO2 reached 91.1% after illumination for 180 min, which was significantly higher than that of TiO2. This work provided a simple method to prepare highly active TiO2-based photocatalysts.