Band gap funning of nanotubular Ti02 by incorporation of Anionic and Cationic Doping
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Date
2010
Authors
Sreekantan, Srimala
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Abstract
Ti02 is the most prom1s1ng semiconductor photocatalyst in the future for environmental
application because of its many excellent properties such as high chemical stability, low cost,
and nontoxicity. However, the utilization of this semiconductor is limited due to poor response to
visible natural solar light. The achievement of high-efficiency under solar light requires a suitable
material with lower band gap energy and suitable architecture that minimizes the recombination
of the photogenerated electron-hole pairs. Therefore we have carried out a detailed
investigation on the electrochemical parameter on the anodization of Ti in aqueous and organic
electrolyte for formation of well aligned Ti02 nanotubes. Ti02 nanoJub_eLWiib_\l_adous_lengfus _
ranging from 400nm up to 18 1-fm were obtained by modifying the electrochemical parameter.
The diameter was able to vary from 20 nm to 130 nm. The mechanism of the growth process
postulated and a basis for optimization of the Ti02 nanotubes geometries was established.
Several attempts have been made to modify the surface and electronic structure of Ti02 with
anionic (carbon) and cationic (tungsten) dopant to enhance its activity in the visible region. The
presence of intermediate energy level either by forming oxygen vacancy or impurities such as
WOJ inhibits the photo-generated electron to recombine with holes and thus extend the life time
of the charge carrier. This shift the optical response of the Ti02 nanotubes from UV to visible light
region. These findings could one day convert the TiO:c photocatalyst to work efficiently under
solar light, enabling its use as a self cleaning and self sterilizing surfaces.