Preparation and characterization of high surface area nanosheet titania
with mesoporous structure
Sorapong Pavasupree
a,b
, Supachai Ngamsinlapasathian
a
,
Yoshikazu Suzuki
a
, Susumu Yoshikawa
a,
⁎
a
Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011, Japan
b
Department of Materials and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi,
Klong 6, Pathumthani, 12110, Thailand
Received 6 September 2006; accepted 23 October 2006
Available online 9 November 2006
Abstract
High surface area nanosheet TiO
2
with mesoporous structure were synthesized by hydrothermal method at 130 °C for 12 h. The samples were
characterized by XRD, SEM, TEM, SAED, and BET surface area. The nanosheet structure was slightly curved and approximately 50–100 nm in
width and several nanometers in thickness. The as-synthesized nanosheet TiO
2
had an average pore diameter about 3–4 nm. The BET surface area
and pore volume of the sample are about 642 m
2
/g and 0.774 cm
3

such as crystallinity, particle size, surface area, and preparation
[11]. In the view point of surface area, nanosheet and nanotubes
(from nanosheet rolling technique) TiO
2
(or titanate) offered
high surface area (about 100–400 m
2
/g) [10,23–31].Inour
previous works, nanofibers TiO
2
were synthesized by hydro-
thermal and post heat-treatments from natural rutile sand,
however, nanofibers TiO
2
had rather low surface area (10–
20 m
2
/g) [32,33].
In this study, high surface area nanosheet TiO
2
with me-
soporous structure (with much higher surface area, 642 m
2
/g)
obtained by hydrothermal at 130 °C for 12 h will be reported.
2. Experimental
2.1. Synthesis
Titanium (IV) butoxide (Aldrich) was mixed with the same
mole of acetyacetone (ACA, Nacalai Tesque, Inc., Japan) to
slowdown the hydrolysis and the condensation reactions [14–16].

composed of nanosheets. The flower-like structure had a diameter
about 500 nm to 2 μm(Fig. 3(a)). The nanosheet structure was slightly
curved and approximately 50–100 nm in width and several nanometers
in thickness (Fig. 3(b–c)). The electron diffraction pattern shown in the
inset of Fig. 3(b) supported that the nanosheet was anatase-type TiO
2
,
which corresponded to the XRD results (low crystallinity of anatase
TiO
2
, Fig. 5). In addition, higher magnification TEM (Fig. 3(c)) image
shows nanopores in the flower-like structure.
Fig. 4 gives the nitrogen adsorption isotherm and the pore size
distribution of the as-synthesized nanosheet TiO
2
. The isotherm shows
a typical IUPAC type IV pattern with inflection of nitrogen adsorbed
volume at P/P
0
about 0.45 (type H
2
hysteresis loop), indicating the
existence of mesopores. The pore size distribution of the sample, as
shown in the inset of Fig. 4, showed that the nanosheet TiO
2
with
narrow pore size distribution had an average pore diameter about 3–
4 nm. The BET surface area and pore volume of the as-synthesized
nanosheet TiO
2

2
had relatively high
crystallinity. The peaks corresponding to rutile TiO
2
appeared at 600 °C
and almost showed rutile TiO
2
structure at 700 °C.
Fig. 6(a–j) shows the SEM, TEM, and SAED images of the
nanosheet TiO
2
calcined for 1 h at 300–700 °C. The nanosheet
structure after calcinations was destroyed and changed to nanorods/
nanoparticles composite with anatase TiO
2
structure at 300–500 °C
(10–15 nm in rods diameter and about 5–10 nm in particles diameter,
Fig. 6(a–f)). The SEM, TEM, and SAED images of the nanosheet TiO
2
calcined at 600 and 700 °C showed almost nanoparticles with a mixture
of anatase and rutile TiO
2
structure (about 10–50 nm in diameter, at
600 °C, Fig. 6(g–h)), and rutile TiO
2
structure (about 40–100 nm in
diameter, at 700 °C, Fig. 6(i–j)).
Fig. 1. Schematic representation of the experimental procedure.
Fig. 2. SEM images of the as-synthesized flower-like nanosheet TiO
2

method at 130 °C for 12 h. The nanosheet structure was
slightly curved and approximately 50–100 nm in width and
several nanometers in thickness. The as-synthesized nanosheet
TiO
2
had an average pore diameter about 3–4 nm. The BET
Fig. 3. (a–c) TEM and (inset of (b)) SAED images of the as-synthesized
nanosheet TiO
2
.
Fig. 4. Nitrogen adsorption isotherm pattern of the as-synthesized nanosheet
TiO
2
(BET surface is 642 m
2
/g), and the pore size distribution of the sample with
pore diameter about 3–4 nm (inset).
Fig. 5. X-ray diffraction pattern of the as-synthesized nanosheet TiO
2
and
nanosheet TiO
2
calcined for 1 h at 300–700 °C.
2975S. Pavasupree et al. / Materials Letters 61 (2007) 2973–2977
Fig. 6. SEM, TEM, and SAED images of the nanosheet TiO
2
calcined for 1 h at 300–700 °C.
2976 S. Pavasupree et al. / Materials Letters 61 (2007) 2973–2977
surface area and pore volume of the sample are about 642 m
2

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