Effect of H2O/TEOT ratio on photocatalytic activity of sol-gel-derived TiO2 powder

Abstract

Effect of water/tetraethyl orthotitanate molar ratio (R) on the formation and morphology of sol-gel-derived titania powder has been studied. Solutions for R of 3 and 5 have been prepared. Initial viscosity of the solutions and viscosity of the gels prepared by aging the solutions for some time were measured. Results revealed that lower gel viscosities lead to better crystallization of the aerogel. Aerogels were dried at 80°C for 24 h and then calcined at 300°C for 1 h to obtain titania powders. The structural and morphological analyses of the powders were performed using X-ray diffraction and scanning electron microscopic characterization techniques. Titania particles obtained after calcination composed of only anatase phase and were in the size range of 9–50 nm. The photocatalytic activity of the powders was evaluated in terms of the degradation of methylene blue (MB) solution under UV (ultraviolet) illumination. A diffuse reflectance spectroscopy was used for the band gap energy measurements. Results revealed that R had a profound effect on the particle morphology and photocatalytic activity of sol-gel-derived titania powders. The titania powders prepared from the solution for R of 5 degraded 99·47% of MB solution under UV illumination in 90 min.