TiO2-SiO2 films from organic-free colloidal TiO2 anatase nanoparticles as photocatalyst for removal of volatile organic compounds from indoor air

Different types of TiO2-SiO2 composites in the form of powder or films have been reported as efficient photocatalysts for decomposition of organic compounds in liquid and gas phase. Herein, we report for the first time on the formation of efficient TiO2-SiO2 films made from acidic organic-free colloidal solution of TiO2 anatase nanoparticles (AS) and mesoporous SiO2 (SBA-15) with 100% loading (TiO2: SiO2 molar ratio 1:1) under simple and low cost procedure. AS was prepared from metatitanic acid precursor using a novel, environmentally friendly approach of TiO2 nanoparticles precipitation with NaOH and peptization with HCI. These AS/SBA-15 films, immobilized by brush deposition on glass carriers, showed total decomposition of toluene and 91% decomposition of formaldehyde as model VOCs in gas phase, at room temperature under UVA irradiation in lab-made batch photoreactor. The trend of photocatalytic efficiency for decomposition of formaldehyde was AS/SBA-15 > P25 > PC500 >AS. The adsorption capability of the AS/SBA-15 was higher in comparison to its pure TiO2 analogues (AS, P25, PC500) in case of toluene. Turnover frequency (TOF) of the AS/SBA-15 was approximately six times higher in comparison to its pure TiO2 analogue AS for toluene and formaldehyde. The potential of AS/SBA-15 for the use in air cleaning devices is finally discussed. (C) 2015 Elsevier B.V. All rights reserved.