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 m2/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.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-1137-3) contains supplementary material, which is available to authorized users.

A facile approach towards increasing the nitrogen-content in nitrogen-doped carbon nanotubes via halogenated catalysts

“…6b). The higher I D /I G value observed from SCNMs-Cl is indicative of the presence of more amorphous carbons [34] or CS in these samples because amorphous carbons are normally inherently disordered giving rise to a strong D-band intensity [35]. This observation supports the greater quantity of amorphous carbon and CS observed from TEM analysis of SCNMs-Cl (Table 2).…”

Recent advances in titanium dioxide/graphene photocatalyst materials as potentials of energy generation

“…TiO 2 nanoparticles when used with multiwalled carbon nanotubes (MWCNTs) produce an improved photocatalytic activity [134]. Some fascinating results with earlier work [134][135][136] using titanium on MWCNTs reported excellent physisorbed systems with improved photoactivity. The reason for the improvement was attributed to the long lifetime of the photoinduced charge carriers that finally yield large quantities of radicals, the CNTs gave added sorption properties, and the composites had greater visible light sorption properties [137,138].…”

TiO2–multi-walled carbon nanotube nanocomposites: hydrothermal synthesis and temporally-dependent optical properties

“…Such defects are the likely origin of the observed photoluminescence at 392 nm and in the wavelength range from 450 to 500 nm. 37 However, it should be noted that although the presence of defects can be easily and efficiently proved by photoluminescence measurements, assignment of the different bands is still an area of intense debate within the literatures, because the photoluminescence can result from defects on the surface of TiO 2 , 38,39 the oxygen vacancies, 40,41 the self-trapped excitons, 38,39 or from the charge carrier trapping, migration, and transfer. 42,43 Variation of photoluminescence intensity may originate from the change of defect state on the shallow level of the TiO 2 surface.…”