Synthesis of Titania/Silica Nanocomposite for Enhanced Photodegradation of Methylene Blue and Methyl Orange Dyes under UV and Mercury Lights

A special sol-gel method is used to successfully synthesize spherical TiO 2 /SiO 2 nanoparticles from titanium tetra-isopropoxide and tetraethoxysilane precursors. The prepared samples were dried at 110 and calcined at 300 , 500 , and 800 . The formed titanium oxide is in a tetragonal structure with significant pure anatase and rutile phase. The estimated particle size of the spherical nanostructure was ~18.40 nm through transmission electron microscopy (TEM) and showed a larger Brunauer Emmett Teller (BET) surface area of 310 m 2 /gm for the sample calcined at 300 . The TiO 2 cores are enclosed within SiO 2 particles with an average crystallite size of 10-20 nm. In atomic force microscopy (AFM) images, the same sample displayed a well-structured and macro-pore-free morphology. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of Ti-O-Ti, Si-O-Si, and Ti-O-Si metal oxide bonds to raise the anatase structure of TiO 2 . The ultraviolet-visible spectroscopy (UV-Vis) of as-synthesized samples reveals the visible absorption region. Photoluminescence spectroscopy (PL) shows a decrease in emission intensity and the emission band splits into sharp peaks to signify the decrease in recombination rate. These properties predict the materials to photo-degrade organic dyes. The material's photocatalytic activity was evaluated for degradation of methylene blue and methyl orange dyes. It is found that the sample calcined at 300 exhibits a better photodegradation for methylene blue (MB, 80-85%) than methyl orange (MO, 70-75%) under mercury light within 2 hours.