- Title
- Template-assisted sol-gel synthesis of carbon doped titanium dioxide nanotubes and their characterization
- Creator
- Takata, Nwabisa
- Subject
- Nanotechnology Titanium dioxide Nanostructures
- Date Issued
- 2017
- Date
- 2017
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10353/13194
- Identifier
- vital:39473
- Description
- This study reveals the effects of doping on the morphological, structural and optical properties of titanium dioxide (TiO2) nanotubes (TNTs), synthesized by sol-gel template-assisted sol-gel technique. The nanotubes (TNTs) were prepared in anodic alumina membranes (AAM) with a pore diameter range of 110-210 nm by using titanium tetra butoxide as a sol-gel precursor and oxalic acid dihydrate as a dopant source. The synthesized nanotubes were evaluated using scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), confocal Raman spectroscopy (CRS) and photoluminescence spectroscopy (PL). SEM analysis has revealed the presence of closely-packed TNTs, with a modal external tube diameters of 150, 170, 210,190 and 210 nm for the un-doped TNTs, 9 mM carbon doped-TNTs (C-TNTs), 27 mM C-TNTs, 45 mM C-TNTs and 75 mM C-TNTs respectively. The diameters are consistent with the AAM diameter range. EDX spectra revealed the presence of Ti peaks at 0.45 and 4.9 keV corresponding to Kα1 and Kβ1 emission lines respectively. Oxygen exhibits a signal at 0.5 keV corresponding to Kα1 emission line. The occurrence of these peaks in the EDX spectra endorses the existence of Ti and O atoms in the prepared titanium dioxide nanotubes. FTIR spectroscopy has revealed the presence of vibration modes at 580-660 cm-1 indicating the presence of Ti-O bonds and additional vibration modes at 2324 cm-1 resulting from C-O stretching in the C-TNTs. The XRD analysis has revealed the presence of a mixed anatase-brookite phase with diffraction peaks at 2θ angles of 25.49⁰, 38.11⁰, 40.60º, 48.14⁰, 54.58⁰, 63.00⁰, 70.11⁰ and 75.66⁰. Additionally, XRD analysis has revealed elongation of lattice parameter “c” from 9.143 to 9.830 Å with carbon concentration increase. Lattice expansion indicates the possibility of carbon substituting oxygen sites. Raman large area scan has revealed the presence of rutile, brookite and anatase for the undoped samples. On doping the rutile phase of TiO2 has shown to be suppressed by the presence of carbon atoms such that the doped samples consist of brookite and anatase phases only. The Eg1 mode of anatase of the undoped TNTs at 153. 78 cm-1 was red shifted by Δ9.78 cm-1 relative to the bulk anatase TiO2. This was attributed to decrease in particle size, presence of brookite and phonon confinement. Upon doping, the 9 mM C-TNTs, 27 mM TNTs and 75 mM TNTs have shown a red shift of Δ0. 09 cm-1, Δ1. 39 cm-1 and 1.81 cm-1 respectively, suggesting the incorporation of carbon in the TiO2 matrix. CRS depth profiling in the XZ direction has also validated the presence of a mixed anatase-brookite phase at Raman active modes 153.19 cm-1, 208.87 cm-1, 404.55 cm-1, 523.26 cm-1 and 648.55 cm-1. Photoluminescence spectra of carbon doped TiO2 showed two emission peaks at 398 nm attributed to annihilation of excitons while the broad peak at 400-460 nm was attributed to the presence of oxygen vacancies. The peak intensity of the 45 mM C-TNTs has shown a lower PL intensity suggesting that efficiency of charge separation was higher and recombination rate was lower than other carbon containing samples.
- Format
- 123 leaves
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
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UFH Department of Chemistry
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | MSc (Chemistry) TAKATA.pdf | 3 MB | Adobe Acrobat PDF | View Details Download |