Solvothermal synthesis of carbon nanotube-B2O3 nanocomposite using tributyl borate as boron oxide source

Article abstract of DOI:10.1016/j.inoche.2007.12.015

Single-walled carbon nanotube-B₂O₃ nanocomposite has been prepared using solvothermal technique. Tributyl borate was explored as the boron oxide reagent using toluene and water as the solvent, respectively. Characterization of the reaction products using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction and thermogravimetric analysis confirmed the formation of the CNT-B₂O₃ nanocomposite. The solvothermal approach may serve as a facile strategy for synthesis of nanocomposites of metal oxides and carbon nanotubes especially when metal alkoxides is utilized as precursor for the metal oxides.

Full text of DOI:10.1016/j.inoche.2007.12.015

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Inorganic Chemistry Communications 11 (2008) 275–278
www.elsevier.com/locate/inoche
Solvothermal synthesis of carbon nanotube-B O nanocomposite using
2
3
tributyl borate as boron oxide source
a,
a
b
*
Aderemi Oki , Luqman Adams , Zhipping Luo
a
Department of Chemistry, Prairie View A&M University, Prairie View, Texas 77446, United States
Microscopy and Imaging Center, Biological Sciences Building West, 119 Texas A&M University, College Station, TX 77843-2257, United States
b
Received 27 September 2007; accepted 15 December 2007
Available online 31 December 2007
Abstract
Single-walled carbon nanotube-B O nanocomposite has been prepared using solvothermal technique. Tributyl borate was
2
3
explored as the boron oxide reagent using toluene and water as the solvent, respectively. Characterization of the reaction products
using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction and thermogravimetric analysis confirmed the for-
mation of the CNT-B O nanocomposite. The solvothermal approach may serve as a facile strategy for synthesis of nanocomposites
2
3
of metal oxides and carbon nanotubes especially when metal alkoxides is utilized as precursor for the metal oxides.
Published by Elsevier B.V.
Keywords: Nanocomposite; Solvothermal; Tributyl borate; Boric oxide; Carbon nanotube
Carbon nanotubes have outstanding mechanical,
electrical, thermal, optical/spectroscopic properties and
chemical reactivity [1–9]. Exploitation of these numerous
potentials for practical purposes has not been fully real-
ized, largely because of the need to control the surface
chemistry in other to effectively modulate specific proper-
ties, most especially in nanocomposites. To effectively
utilized CNTs in inorganic matrix, we have to signifi-
cantly modify the surface for matrix compatibility and
ease of dispersion.
to solvents and chemicals, additionally it is a useful clad-
ding material over the core material with a lower refrac-
tive index as wave guides in the transmission of
electromagnetic waves in optical communication systems
[17]. Therefore, deposition of boron oxide on carbon
nanotubes surface can produce a new range of materials
with potential application in nanoelectronics technology
[18–22]. Previously, the synthesis of CNTs-B O nanocom-
2
3
posite required the autoclaving of commercially available
B O with CNTs [23]. In this communication, we report
2
3
Various strategy have been reported in modulating
surface of CNTs to improve matrix dispersion, such tech-
niques includes covalent functionalization [10,11], coating
of various inorganic compounds, for example, nanoparti-
cle oxides of Al(OH) , Al O , SnO , SiO , and TiO in
a facile approach to coat CNTs with boric oxide powder
starting from (less expensive) boric acid to obtain CNTs-
B O nanocomposite. Carbon nanotubes used in this work
2
3
was obtained from Carbon nanotubes Inc. (CNI, USA),
from lot # XD 3365 A, which contains, about 33% sin-
gle-walled CNTs and some double and multi walled car-
bon nanotubes and less than 55 metal oxide impurities.
The synthesis of (n-C H O) B precursor was accomplished
3
2
3
2
2
2
order to expand the scope of their potential applications
12–16]. Boric oxide is an important refractory material,
[
and when in the glassy crystalline state shows resistance
4
9
3
using the modified literature procedure as reported [24].
The CNTs-B O nanocomposite was prepared using
*
2
3
Corresponding author. Tel.: +1 1 936 261 3105; fax: +1 1 936 261
solvothermal process, with toluene serving as the solvent
24].
3
117.
[
E-mail address: aroki@pvamu.edu (A. Oki).
1387-7003/$ - see front matter Published by Elsevier B.V.
doi:10.1016/j.inoche.2007.12.015

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A. Oki et al. / Inorganic Chemistry Communications 11 (2008) 275–278
4
5 kV and 40 mA with copper ka radiation. The analysis
B
3
+
H O
2
B(OH)3 + 3
OH
O
1
2
indicates that the most intense peak corresponds to the
boron oxide in Fig. 3.
i. Toluene, sonicate 30mins
The TEM picture of the CNTs-B O is shown in
2
2
ii.
B
o
*
O
/140 C/72h
Fig. 4, and clearly shows that the coatings of CNT with
boron oxide also help detangled and un-roped the car-
bon nanotubes. The thermogravimetric analysis (TGA)
performed on approximately 10 mg samples is shown
in Fig. 5. The run consisted of a ramp at a steady rate
of 25 °C/min from 40 °C to 800 °C in nitrogen. The
analysis shows two sharp weight losses at about
3
CNTs
=
B O
2
CNTs-B O3
2
3
Fig. 1. Reaction schemes for tributyl borate mediated SWCNT-B
2 3
O
nanocomposite.
100 °C and 620 °C, respectively. The first weight loss
of about 27% is likely due to solvents, while the second
weight loss is probably due to oxidation of exposed car-
bon on the CNTs defect sites. The TGA analysis of
pristine CNTs (not shown) shows one sharp weight loss
that drops to about 2% at 600 °C. We can infer from
the residual weight loss for the nanocomposite that the
surface B O prevents complete decomposition of the
2
3
carbon nanotubes [23]. The reaction of tributyl borate
with CNTs under similar condition but utilizing water
as the solvent (hydrothermal) was also explored as a
strategy to the desired CNTs-B O nanocomposite.
2
3
However, this approach resulted in the hydrolysis of
tributyl borate to boric acid, and the deposition of boric
acid on CNTs.
2 3
Fig. 2. FTIR of CNTs coated with B O compared with neat CNTs.
In summary, we have reported a simple technique to
coat CNTs with B O with potential applications in
2
3
nanocomposite technology. This method can also be uti-
lized to improve the dispersion of CNTs in inorganic
matrix and may generally be extended to other metal oxi-
des. We are currently investigating the potential applica-
tions of this materials in nanoelectronic industry. It is
envisioned that this solvothermal approach may serve
as a facile strategy for synthesis of nanocomposites of
metal oxides and carbon nanotubes using metal alkoxides
as starting reagents.
The synthesis of CNTs-B O nanocomposite based
on the facile solvothermal protocol is summarized in
Fig. 1.
2
3
The FTIR spectra of the nanocomposite materials are
shown in Fig. 2. The spectrum for CNTs-B O shows
2
3
À1
B O characteristic peaks at 1458, 1195, and 795 cm
,
2
3
respectively [25]. X-ray powder diffraction data identify
the B O crystalline phase present in the sample under
2
3
2 3
Fig. 3. X-ray powder diffraction analysis of CNTs-B O confirms boron oxide.

A. Oki et al. / Inorganic Chemistry Communications 11 (2008) 275–278
277
2 3
Fig. 4. TEM of CNTs-B O nanocomposite.
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Appendix A. Supplementary material
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.inoche.2007.
3 3 4 9
of H BO , 87.43 g (1179.51 mmol) of n-C H OH and 50 ml of
toluene. The resulting mixture was heated at 130 °C for 5 h. The
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A. Oki et al. / Inorganic Chemistry Communications 11 (2008) 275–278
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