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Visible light-sensitive carbon doped titanium dioxide nanoparticles (C-TiO
2
) were prepared by a
sol-gel method. The carbon dopant was obtained from glucose. The dopant level incorporated into
the TiO
2
lattice structure was varied by using different concentrations of the carbon source solution.
The nanoparticles were characterized by X-ray diffraction (XRD), BET Surface area, Scanning
electron microscopy (SEM), Transmission electron microscopy (TEM), Scanning X-ray
photoelectron spectroscopy (SXPS) and Diffuse reflectance spectroscopy (DRS). The presence of
carbon in the TiO
2
lattice was determined by SXPS. The DRS results revealed that carbon doping
reduced the band gap of TiO
2
. Doping was also found to cause a reduction in the particle size of the
TiO
2
nanoparticles and enhance anatase to rutile phase transformation. The photocatalytic activities
of the prepared samples were evaluated by the photocatalytic degradation of methyl orange. The
carbon doped TiO
2
showed a higher photocatalytic activity than degussa P25 and undoped TiO
2
.
Titanium dioxide (TiO
2
) has been of great interest in heterogeneous photocatalysis because of its
properties such the high oxidation power of its photogenerated holes, excellent long term chemical
stability, non-toxicity and relative low cost [1, 2]. Different forms of TiO
2
especially anatase have
been used in the preparation of self-cleaning coatings [3], environmental purification [4],
decomposition of organic compounds and other contaminants [5, 6] using solar irradiation. Frank
and Bard reported that some cyanides could be photocatalytically oxidised using TiO
2
in aqueous
medium [7]. The rutile phase is mainly used as a white pigment due to its good scattering effect
which protects materials from UV light [8].
There are several ways of improving the photacatalytic activity of TiO
2
nanoparticles and these
include, (i) use of supports such as carbon nanofibres [9], zeolites [10], mesoporous sieves [10] and
silica, [11] (ii) increase in surface to volume ratio by developing other nanosize geometries in
particular nanotubes [12,13] nanorods [14] cubical morphology [15].
The major drawback in the use of TiO
2
is its wide band gap (ca. 3.2 eV for the anatase crystalline
phase and 3.0 eV for the rutile phase) meaning it is only activated under UV illumination which is
only about 5 % of the total solar radiation. In order to utilise the visible light, the TiO
2
photocatalyst
is generally modified using various methods such as transition metal doping [16] and dye
Materials Science Forum Vol. 712 (2012) pp 49-63
Online available since 2012/Feb/27 at www.scientific.net
© (2012) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/MSF.712.49
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
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