China Received 29 November 2005; received in revised form 11 January 2006; accepted 5 February 2006 Available online 20 March 2006 Abstract TiO2 nanofibres were synthesized by the hydrot
Trang 1Hydrothermal synthesis of TiO 2 nanofibres
Fei-Bao Zhang, Hu-Lin Li ⁎
College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P.R China Received 29 November 2005; received in revised form 11 January 2006; accepted 5 February 2006
Available online 20 March 2006
Abstract
TiO2 nanofibres were synthesized by the hydrothermal method The result shows that the growth of TiO2 nanofibres is sensitive to the concentration of NaOH and the heating temperature
© 2006 Elsevier B.V All rights reserved
Keywords: Nanofibres; Transmission electron microscopy; X-ray diffraction
1 Introduction
Investigation on TiO2 has been attracting worldwide interest
during the past decades[1–3]for its promising application in light
emission, gas sensors, catalyst and solar cells Low dimensional
nanostructures materials have shown many advantages Low
di-mensional CdSe nanorods have been reported to be better in solar
energy conversion for their single-crystal structures can supply a
directed path for electron transport[4] A more than 2-fold increase
in maximum photoconversion efficiency for water splitting has
been observed by replacing TiO2nanocrystalline films with TiO2
nanowires [5] Thus designing novel TiO2 nanostructures,
especially well-defined anisotropic and low dimensional
nanos-tructures, is of significant importance for fundamental research as
well as various relevant applications Up to now, different methods
have been used to synthesize the low dimensional TiO2 Growth of
1-D TiO2nanostructures, including nanowires and nanotubes, has
been demonstrated using sol–gel, electrodeposition, and
hydro-thermal methods with or without anodic aluminum oxide (AAO)
[6–9] TiO2nanorods have also been grown on a WC-Co substrate
by metalorganic chemical vapor deposition (MOCVD) using
tita-nium-tetraisopropoxide (TTIP) as the precursor[10]
In this paper, we report a novel strategy to synthesize TiO2
nanofibres under hydrothermal conditions in alkaline solution
Compared with the other reporters who use hydrothermal
me-thod to synthesize TiO2, the reaction temperature we used was
higher while the concentration of NaOH was lower To our knowledge, there are few reports about synthesizing TiO2 na-nofibres based on the hydrothermal method This method may open a new door to synthesize novel morphology via changing some conditions
2 Experimental The titanium dioxide (TiO2, anatase) and sodium hydroxide (NaOH) are obtained as analysis pure grade and used without
⁎ Corresponding author Tel.: +86 931 891 2517; fax: +86 931 891 2582.
E-mail address: lihl@lzu.edu.cn (H.-L Li).
0 10 20 30 40 50 60 70 80 90
2 θ/degree
(2 1 1) (1 0 5) (2 0 0) (0 0 4) (1 0 0)
Fig 1 XRD patterns for the sample.
0928-4931/$ - see front matter © 2006 Elsevier B.V All rights reserved.
doi: 10.1016/j.msec.2006.02.001
Trang 2further purification and treatment TiO2 nanofibres were
synthesized in a typical procedure 0.2 g TiO2 (anatase)
powder was put into a Teflon-lined stainless steel autoclave of
30 ml capacity The autoclave was filled with 1 M NaOH
solutions up to 80% of its capacity, maintained at 160 °C for
24 h, and then cooled to room temperature naturally A white
precipitation was filtered and washed with distilled water and absolute ethanol in sequence Finally, the products were dried
at 50 °C The structure and morphology of products were characterized by several techniques Powder X-ray diffraction (XRD) data were collected using a Rigaku D/MAX 2400 dif-fractometer with Cu-Kα radiation (λ=1.5418 Å) Transmission
Fig 2 TEM images of TiO nanofibres (A) Scale bar = 1 μm; (B) scale bar=167 nm; (C) scale bar=286 nm; (D) scale bar=200 nm; (E) scale bar=3.3 μm.
Trang 3electron microscopy (TEM; Hitachi 600, Japan) was used to
observe the morphology
3 Results and discussion
Fig 1 shows the X-ray powder diffraction pattern of the
product It is identified as pure TiO2(JCPDS card no 21-1272)
The crystalline structure of TiO2 powders was further
cha-racterized by using an X-ray diffractometer as shown inFig 1
All these diffraction peaks, including not only the peak
posi-tions but also their relative intensities, can be perfectly indexed
into the crystalline structure of anatase TiO2 The result is in
accordance with the standard spectrum (JCPDS, card no
21-1272)
The morphologies of the as-prepared products were
inves-tigated by transmission electron microscopy (TEM; Hitachi
600, Japan).Fig 2shows a TEM micrograph for the product
One can see that the product consists of entangled fibres.Fig 2
(E) shows a TEM micrograph for “analytically pure” TiO2
commercial powder The particle size is about 10μm
Compared with Kasuga et al [7], who have prepared
titanium oxide nanotubes with a diameter of ≈8 nm and a
length of ≈100 nm when sol–gel-derived fine TiO2-based
powders were treated chemically (e.g., for 20 h at 110 °C) with a
5–10 M NaOH aqueous solution, we have prepared TiO2
na-nofibres with lower concentration of NaOH and higher
tem-perature The experiment was also carried out with different
concentrations of the alkali and at different temperatures These
TiO2 nanofibres can be formed via the hydrothermal method
when the concentration of the alkali is about 1 M and the
temperature is not less than 160 °C If the concentration of the
alkali increased and the temperature was about 110 °C, short
TiO2nanotubes were formed Thus the growth process of TiO2
nanofibres is controlled by the concentration of the alkali and temperature Micron-sized TiO2is used as the precursor in this work, while in other experiments the nanoscale TiO2is used
4 Conclusion
In conclusion, TiO2nanofibres are successfully synthesized
by using lower concentration of NaOH and higher temperature Given the generality of this attempt, we hope to extend our synthetic method to prepare other 1-D nanostructure materials Acknowledgements
This work is supported by the National Natural Science Foundation of China (NNSFC No 60471014)
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