Combined modification of a TiO2 photocatalyst with two different carbon forms

Abstract

Hydrothermally synthesized titanate nanotubes were carbon-doped through a thermal treatment in the presence of glucose followed by blending with single-walled carbon nanotubes (SWCNTs). A series of TiO 2 -based materials was prepared with various initial glucose contents and two SWCNT types, resulting in total carbon contents from 0.3 wt.% to nearly 26 wt.%. Electron microscopy observations indicated that titanate nanotubes were converted into nanorods during the thermal treatment, and X-ray diffraction patterns confirmed that all the treated materials mostly consisted of anatase TiO 2 . Glucose pyrolisis caused changes in the infrared and X-ray photoelectron spectra of the titania material, indicating an interaction between the inserted carbon atoms and titanium atoms. Raman spectra of SWCNT/C/TiO 2 hybrids showed characteristic bands of both the SWCNT and anatase TiO 2 phases. SWCNT/C/TiO 2 multicomponent materials demonstrated substantially better photocatalytic activities than P25 TiO 2 for methylene blue degradation under visible light irradiation. Independently from its origin, the presence of carbon caused a strong increase in the TiO 2 visible light absorption. However, the results obtained with the C/TiO 2 and SWCNT/C/TiO 2 photocatalysts clearly showed different photocatalysis mechanisms depending on the carbon form.

Laser oxidative pyrolysis synthesis and annealing of TiO2 nanoparticles embedded in carbon–silica shells/matrix

“…The large peak around 690-700 cm −1 was fond also in flame-made titania FTIR spectrum and attributed to Ti O Ti bonding [9]. Another intense peak, found also for all samples around 460-510 cm −1 and may be a signature from Ti O bonds, reported also for titania thin films [43] at 430 cm −1 or nanotubes [44] at 496 cm −1 . In the same article [44], for titania-carbon nanocomposite, a strong IR line at 488 cm −1 was attributed to Ti C bond.…”

“…Another intense peak, found also for all samples around 460-510 cm −1 and may be a signature from Ti O bonds, reported also for titania thin films [43] at 430 cm −1 or nanotubes [44] at 496 cm −1 . In the same article [44], for titania-carbon nanocomposite, a strong IR line at 488 cm −1 was attributed to Ti C bond. Finally, for TLOP 8 sample, another peak at 460 cm −1 can be identified, close to the Si O Si bending mode peak at 470 cm −1 observed in the laser-synthesized oxygen-deficient titania-silica powders [30].…”

Multiwalled carbon nanotube-titania nanocomposites: Understanding nano-structural parameters and functionality in dye-sensitized solar cells

“…Some of the reasons for the improvement in performance include superior characteristics regarding separation of charge carriers within the nanocomposite, 12 excellent electrical conductivity, and a relatively large surface area for physico-chemical processes. Several examples that utilize TiO 2 /CNT nanocomposites have been reported in literature, and these include research on photo-catalysis, [13][14][15][16][17][18][19] electrochemical energy conversion 20 and storage, 21 and dye-sensitized solar cells. 10,14,22,23 Carbon nanotubes can be simply described as a rolled up sheet of graphene, and based on the number of sheets they can be classified as single, double, and multiwalled CNTs.…”

“…Use of MWCNTs in DSSCs is an active area of research, and early work in this field used MWCNTs in DSSCs as either a counter electrode, 25 an additive, 26 or as a nanocomposite material. [27][28][29] MWCNT-titania nanocomposites have been fabricated by a number of ways such as sol-gel, 30 mechanical mixing, 10 electro-spinning, 14,23 electrophoresis deposition, 31 novel surfactant solgel wrapping, 18 blending, 13 physical vapour deposition, sputtering deposition, 16 supercritical fluid deposition, 19 capillary action, hydrothermal 32 and chemical vapour deposition (CVD). 33 MWCNTs agglomerate easily and extra care must be taken to ensure that the nanotubes disperse homogeneously within a matrix of interest.…”

Preparation and characterization of titanium dioxide modified with carbon with enhanced photocatalytic activity

“…Diffractograms of all powders show intensive peaks which belong to anatase phase ( Fig. 1 b) as in works [1,3,4]. No signal of brookite or rutile is detected by XRD.…”