Synthesis, characterization and enhanced photocatalytic activity of TiO2/SiO2 nanocomposite in an aqueous solution and acrylic-based coatings

In this study, TiO2/SiO2 nanocomposites were synthesized via a sol–gel route by adding tetraethylorthosilicate (TEOS) to a solution containing different molar ratios of Degussa P25 TiO2 nanoparticles. FTIR, TGA, EDAX and XRD techniques were used to characterize the modified nanoparticles. Photocatalytic activity of the nanoparticles in an aqueous solution and into the acrylic based coating was evaluated using colour coordinate data measurements, SEM analysis, gloss measurements and FTIR spectroscopy, in the presence of Rhodamine B (Rh.B) dyestuff, as a pollutant model, before and after exposure to the UVA (340 nm) irradiation and compared to their unmodified counterparts.The results showed that silica grafting effectively reduced the photocatalytic activity of the TiO2 nanoparticles as evidenced by absorption spectra and colour changes of Rh.B aqueous solutions during the UVA irradiation. The results revealed the effectiveness of sol–gel route for preparation of TiO2/SiO2 nanocomposites. The optimum result was obtained with 1% molar ratio of TiO2:TEOS. Addition of TiO2/SiO2 nanocomposites into the acrylic based coating revealed reduction of photo-degradation of Rh.B compared to untreated nanoparticles. Finally, inclusion of TEOS treated TiO2 nanoparticles into the aqueous organic coatings, provides photocatalytic property and as a result, it can possibly be considered for self-cleaning coatings.

► This paper reports an efficient approach for silica grafting of TiO2 nanoparticles. ► The silica treatment of TiO2 nanoparticles was confirmed using various techniques. ► Silica grafting effectively reduced photocatalytic activity of TiO2 nanoparticles. ► Proper photocatalytic property of acrylic coatings was obtained using treated TiO2. ► Barrier silica layer delays degradation of C–C bond on the acrylic based coatings.