Photo-Catalytic Properties of TiO(2) Supported on MWCNTs, SBA-15 and Silica-Coated MWCNTs Nanocomposites

Mesoporous silica, specifically SBA-15, acid-treated multi-walled carbon nanotubes and a hybrid nanocomposite of SBA-15 coated onto the sidewalls acid-treated multi-walled carbon nanotubes (CNTs) were prepared and used as supports for anatase TiO(2). Sol-gel methods were adapted for the synthesis of selected supports and for coating the materials with selected wt% loading of titania. Physical and chemical properties of the supports and catalyst composite materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectroscopy and fluorescence spectroscopy. The photo-activity of the catalyst composites were evaluated on the decolorisation of methylene blue as a model pollutant. Coating CNTs with SBA-15 improved the thermal stability and textural properties of the nanotubes. All supported titania composites had high surface areas (207–301 m(2)/g), altered band gap energies and reduced TiO(2) crystallite sizes. The TiO(2)/SBA-CNT composite showed enhanced photo-catalytic properties and activity than the TiO(2)/SBA-15 and TiO(2)/CNT composites. In addition, an interesting observation was noted with the TiO(2)/SBA-15 nanocomposites, which had a significantly greater photo-catalytic activity than the TiO(2)/CNT nanocomposites in spite of the high electron-hole recombination phenomena observed with the photoluminescence results. Discussions in terms of morphological, textural and physical-chemical aspects to account for the result are presented. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s11671-015-1137-3) contains supplementary material, which is available to authorized users.