Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Synthesis of anatase TiO 2 nanotubes at high temperature by sol-gel template method
Elaheh Ghorbani 1, * , Leili Motevalizadeh 1, * , Nasser Shahtahmassebi 2 , Ebrahim Attaran 2
1 Department of physics, Faculty of science, Islamic Azad university, Mashhad branch, Mashhad, Iran.
2 Department of physics, Ferdowsi university of Mashhad, Mashhad, Iran.
Abstract—The anatase phase of TiO 2 nanotubes have been synthesized by sol-gel template method using alumina membrane
as a template after annealing at 800°C for 2 hours. Transmission electron microscopy (TEM) and X-ray diffraction were used
to investigate the structure and morphology of the TiO 2 nanotubes. TEM image showed that the obtained TiO 2 nanotubes were
highly ordered and uniform. The diameter and length of the obtained nanotubes were determined by the pore size and the
thickness of AAO template. XRD results showed that the TiO 2 nanotubes were crystallized in anatase phase after annealing at
800°C for 2 hours.
TiO 2 is one of the semiconductor materials that are widely
investigated due to important applications in many fields such
as gas sensors, solar cells and photocatalysts [1, 2]. Most of
these applications are a consequence of its chemical stability,
high photocatalytic activity and surface reactivity [3, 4].
Recently, much effort has been devoted to preparation of TiO 2
nanotubes that have larger surface area compared to TiO 2
nanoparticles and bulks. These structures should enhance
surface related properties such as catalytic activity and surface
adsorption [5].
One of the most important methods for synthesis TiO 2
nanotubes is the template assisted method due to controlling
the morphology and arrangement (1D) nanostructures in
which the diameter, length and aspect ratio of the obtained
structures are fully controlled by the templates used [6]. This
method combines the sol-gel processing and template-based
growth. In this manner, the template is dipped directly into
TiO 2 -sol solution with an appropriate deposition time, sol
particles can fill channels of template and form structures with
high aspect ratio. The final product will be obtained after a
thermal treatment to remove the gel [7].
In this paper the TiO 2 -sol is formed by mixing of
titanium tetra isopropoxide and 2-propanol at molar ratios of
1:20. The mixture was then stirred for 3 h at the room
temperature.
For the synthesis of nanotubes, the porous anodic
alumina membranes (Whatman Anodisc 25) were used as the
template. The average thickness, and pore size of these
templates were 60 μm and 150–200 nm, respectively. The
alumina template membranes were dipped into sol solution for
5 min, then the samples were dried in air at room temperature
for 30 min. For thermal treatment, the prepared specimens
were placed in a furnace (in air) and the samples warm up to
200°C in less than 5 min, then they were heated up at a rate of
2°C/min in 800°C and were held in this temperature for 2 h.
Finally, the furnace was shut down and the samples were
cooled down to room temperature. The fig 1 shows the XRD
patterns of samples annealed at 800°C for 2 h. we have to
notice that these samples are include of AAO membrane and
polycrystalline TiO 2 nanotubes. The peak positions and their
relative intensities are consistent with the standard powder
diffraction pattern of anatase TiO 2 . Sadeghzade Attar et al.
reported the formation of anatase TiO 2 in annealing
temperature between 400 to 600°C and in 800°C the phase of
TiO 2 was reported rutile[8]. But in this work the phase of TiO 2
has been changed from rutile to anatase in this annealing
temperature.
Fig. 2 shows TEM images of obtained TiO 2 nanotubes.
They have a wall thickness about 10 nm and a diameter of
around 200 nm, which correspond exactly with the pore size
of the AAO membrane. This indicates that the diameter of the
nanotube synthesized is controlled by the pore size of
aluminum oxide membrane.
Fig. 1 XRD pattern of sample that include TiO 2 nanotubes and AAO
template.
200 nm 500 nm
Fig. 2 TEM images of TiO2 nanotubes
In this study, TiO 2 nanotubes have been synthesized by
sol-gel chemical method within the pores of AAO template
membrane. The results of XRD showed that the obtained TiO 2
nanotubes are polycrystalline with anatase phase after
annealing at 800ºC for 2h. The TEM images showed the
average diameter of nanotubes were about 200 nm in diameter
with several micrometers in length. It was shown that the
dimension of nanotubes depends on the pore size of the
template.
*Corresponding author: lmotevali@mshdiau.ac.ir, e.ghorbani80@gmail.com
[1] E. Palomares, R. Vilar, J.R. Durrant, Chem. Commun. 4 (2004) 362.
[2] B. O , Regan, M. Gratzel, Nature (1991) 353.
[3] A-W. Xu, Y. Gao, H-Q. Liu, J Catal 207(2002)151.
doi:10.1006/jeat.2002.3539.
[4] M. Keshmiri, M. Mohseni, T. Troczynski, Appl Catal Environ
53(2004)209. doi: 10.1016/j.apcatb.2004.05.016
[5] E. Comini, C. Baratto, G. Fglia, M. Ferroni, A. Vomiero, G. Sberveglieri,
Progress in material science 54 (2009) 1.
[6] John C. Hulteen and Charles R. Martin, J. Mater. Chem. 7 (1997) 1075.
[7] B.B. Lakshmi, C.J. Patrissi, C.R. Martin, Chem. Mater. 9 (1997) 2544.
[8] A. Sadeghzadeh Attar, M. Sasani, F. Hajiesmaeilbaigi, Sh. Mirdamadi,
K.Katagiri, K. Koumoto; J Mater Sci 43 (2008) 5924.
6th Nanoscience and Nanotechnology Conference, zmir, 2010 379