Influence of TiO2 phase composition on the photocatalytic activity of TiO2/MWCNT composites prepared by combined sol-gel/hydrothermal method

Titanium dioxide/multiwall carbon nanotube (TiO2/MWCNT) composites were prepared by sol-gel method with hydrolysis of titanium alkoxide precursor followed by crystallization via hydrothermal treatment at different acid concentrations. Transmission electron microscopy (TEM) measurements revealed that the acid concentration has serious control over the morphology which is in good agreement with the change of specific surface area. According to the X-ray diffraction analysis of the samples the anatase/rutile ratio of the TiO2 in the composite can be tuned by the manipulation of acid concentration used for the hydrothermal crystallization. Samples were tested in aqueous-phase photocatalytic degradation reaction of salicylic acid in a batch-type foam reactor using relatively low power UV-A irradiation. The change in salicylic acid concentration was monitored by UV-vis spectroscopy technique. Anatase/rutile ratio decreased with increasing acid concentration and photocatalytic performance was decreased with increasing rutile content, however low rutile content (11 wt%) enhanced the photocatalytic efficiency above all prepared samples. (C) 2016 Elsevier B.V. All rights reserved.