title: Photo-Catalytic Properties of TiO2 Supported on MWCNTs, SBA-15 and Silica-Coated MWCNTs Nanocomposites.
abstract: 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 TiO2. 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 TiO2 crystallite sizes. The TiO2/SBA-CNT composite showed enhanced photo-catalytic properties and activity than the TiO2/SBA-15 and TiO2/CNT composites. In addition, an interesting observation was noted with the TiO2/SBA-15 nanocomposites, which had a significantly greater photo-catalytic activity than the TiO2/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.
authors.affiliation: School of Chemistry, University of KwaZulu-Natal, Westville Campus, Durban, South Africa.
authors.forename: Nteseng O
authors.initials: NO
authors.lastname: Ramoraswi
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein, Johannesburg, 2028, South Africa. pndungu@uj.ac.za.
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Ndungu
keywords: Carbon nanotubes; Mesoporous; Photo-catalyst; SBA-15; SBA-MWCNT composite; Titanium dioxide