Solution-phase template approach for the synthesis of Cu2S nanoribbons

Article abstract of DOI:10.1039/b512205h

In this paper, we have developed a solution-phase template approach to synthesize Cu₂S nanoribbons for the first time. Bi₂S ₃ nanoribbons act as both template and reactant when treated with small CuCl particles, generating Cu₂S nanoribbons with the assistance of the solvent ethanol. Nanoribbons with different compositions of Bi ₂S₃ and Cu₂S also could be obtained through controlling the reaction time. This kind of template method is expected to be a general template approach due to its slow reaction rate and simplicity. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b512205h

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Solution-phase template approach for the synthesis of Cu S nanoribbons
2
Zhengquan Li,a,b Huan Yang, Yue Ding, Yujie Xiong† and Yi Xie*
b
b
b
a,b
Received 30th August 2005, Accepted 26th October 2005
First published as an Advance Article on the web 10th November 2005
DOI: 10.1039/b512205h
In this paper, we have developed a solution-phase template approach to synthesize Cu
for the first time. Bi nanoribbons act as both template and reactant when treated with small CuCl
particles, generating Cu S nanoribbons with the assistance of the solvent ethanol. Nanoribbons with
different compositions of Bi and Cu S also could be obtained through controlling the reaction time.
2
S nanoribbons
2
S
3
2
2
S
3
2
This kind of template method is expected to be a general template approach due to its slow reaction
rate and simplicity.
Introduction
It is known that solid-state reactions generally proceed at a
slow rate that facilitates control over chemical composition, but
has the shortcoming that it generally produces solid-state by-
products. Following the idea that by-products can be rationally
removed by solvent in reaction processes, solid-state powders
with specific nanostructures can be used as reactants as well as
templates in the solution-phase. In this paper, we report the design
In recent years, one-dimentional (1D) nanostructures such as
nanorods, nanowires and nanotubes have been shown to exhibit
superior electrical, optical, mechanical and thermal properties,
and are expected to be used as fundamental building blocks for
1,2
nano-scale science and technology. As a notable kind of 1D
nanostructure with special geometrical shapes, nanoribbons (or
nanobelts) have a rectangular cross section with a high surface-
to-volume ratio, and thus show many potential applications in the
of a novel solution-phase template approach to synthesize Cu
nanoribbons. This new strategy could be illustrated as follows:
2
S
3,4
field effect transistors and gas sensors etc. Previous research has
promoted several approaches for the synthesis of nanoribbons,
such as the vapor–liquid–solid process, hydrothermal synthesis,
etc., in which a variety of nanoribbons have been successfully
Bi
2
S
3
+ 6CuCl ꢀ 3Cu
2
S ↓ + 2BiCl
3
In this reaction, solid-state Bi
2
S
3
nanoribbons were used as both
template and reactant that reacted with solid-state CuCl thin
particles with the assistance of the solvent ethanol, as the by-
5–8
obtained. In general, the growth in the above cases was directed
by the anistropic crystal structures under specific conditions. But,
as it is hard to find a template as scaffold within which the
as-desired materials can be generated in situ and shaped into
ribbons, the template approach has seldom been used to fabricate
nanoribbons. Therefore, the development of effective template
approaches toward nanoribbons is of great significance.
product BiCl
ultra-long Cu
morphology to the reactant Bi
our knowledge, this is the first synthesis of Cu
3
could be completelydissolved inethanol. As a result,
S nanoribbons were synthesized with a similar
nanoribbons. To the best of
S nanoribbons.
2
2
S
3
2
This kind of template method is expected to be a general template
approach due to its slow reaction rate and simplicity.
Transition-metal chalcogenide nanocrystals have been exten-
sively investigated for their potential applications to catalyst,
Experimental
9,10
solar cell, photoluminescence and optical devices. As a type of
indirect bandgap semiconductor, Cu S nanocrystals are expected
to be a distinguished candidate for optical devices. In the
past few years, several kinds of Cu S nanocrystals, including
nanorods and nanowires, have been synthesized. As examples,
Cu S nanorods, nanodisks and nanoplates were prepared via
pyrolysis of precursors.
also obtained through a gas–solid reaction on copper foil, and
The reactant Bi
2
S
3
nanoribbons were synthesized according to the
2
16
11
literature. Then the Bi nanoribbons (0.5138 g, 1 mmol) and
2
S
3
excess ground CuCl powder (1.5905, 10 ml) were mixed and loaded
in a 60 mL Teflon-lined autoclave which was filled with 50 mL
absolute ethanol. The autoclave was sealed and maintained at
2
2
◦
12,13
120 C for 2 days, and then cooled to room temperature naturally.
Well-arranged Cu S nanorods were
2
The precipitate was filtered off, washed with dilute HCl, distilled
water, ammonia and absolute ethanol (to remove the by-products)
several times, respectively, and dried under vacuum. The yield of
14,15
their field emission properties were also investigated.
However,
the synthesis of Cu
up to now.
2
S nanoribbons still remains largely unexplored
Cu
Bi
2
S nanoribbons was approximately 82% referred to reactant
S .
3
2
a
School of Chemical and Material Engineering, Southern Yangtze Univer-
sity, Wuxi, Jiangsu, 214036, P. R. China. E-mail: yxielab@ustc.edu.cn;
Fax: +86-551-3603987; Tel: +86-551-3603987
Results and discussion
The X-ray powder diffraction (XRD) analysis was performed on a
Phillps X’pert PRO SUPPER diffractor equipped with Ni-flitered
b
Nano-materials and Nano-chemistry, Hefei National Laboratory for Phys-
ical Sciences at Microscale, University of Science and Technology of China,
Hefei, Anhui, 230026, P. R. China
†
˚
Cu-Ka radiation (k = 1.54178 A). The XRD patterns of prepared
products are shown in Fig. 1. All the peaks in Fig. 1 could be
Present address: Department of Chemistry, University of Washington,
Seattle, WA, 98195-1700, USA.
clearly indexed to the pure cubic phase of Cu
2
S (JCPDS 84–1770)
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Dalton Trans., 2006, 149–151 | 1 4 9

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Cu
2
S crystal. Note that the as-prepared Cu
2
S nanoribbons have
inherited the length, width and thickness of those of the reactant
Bi nanoribbons, suggesting that the Bi nanoribbons have
2
S
3
2
S
3
acted as effective templates in the reaction process.
In the whole reaction process, only the by-product BiCl could
3
be dissolved in ethanol, which reduced the Gibbs Energy of this
reaction and ensured the completeness of the solid–solid reaction.
If water was used as solvent, this reaction could not happen
because all the reactants and products could not be dissolved in it.
+
On the other hand, when Cu solution was used instead of CuCl
2
Fig. 1 XRD patterns of prepared Cu S nanoribbons.
particles, no Cu
liquid reaction between solid Bi
happen under the same conditions. The above results suggest that
the reaction between Bi and CuCl was a solid–solid one, which
2
S was produced either, indicating that a solid–
+
˚
2
3
S and Cu in solution did not
with lattice constants a = 5.628 A. No peaks for other types of
Cu S or impurities were observed in the XRD patterns, indicating
high purity and crystallinity of the products.
2
2
S
3
could increase the reaction entropy more than a solid–liquid or
liquid–liquid interaction.
In order to investigate the possible formation mechanism of the
The morphologies of the products were investigated by the
field emission scanning electron microscope (FESEM, JEOL-
6
300). A typical FESEM image of the products is shown in
Cu S nanoribbons, we took samples at different reaction stages.
2
Fig. 2A, revealing that the products consist of long wire-like
structures. From the magnified FESEM image shown in Fig. 2B,
one can clearly see that the thickness of the wire-like structures
is different from their width, indicating that the products were
The products at t = 8 h, 16 h and 24 h were collected, whose
morphologies were also investigated by FESEM. The FESEM
results indicated that no distinct morphologies were found in these
intermediate products. A typical morphology of the intermediate
product obtained at t = 16 h was shown in Fig. 3. From the
panoramic image (Fig. 3A), one could see that the intermediates
were composed of nanoribbons and irregular particles. Careful
observation of the nanoribbon shown in Fig. 3B (and the inset)
reveals that the surface of the nanoribbons are also covered by
many thin nanoparticles. This indicates that the the small CuCl
of Cu S nanoribbons rather than nanowires. Observation of a
2
single nanoribbon is shown in Fig. 2C, showing the characteristic
morphology of the ribbon-like structure. The thickness and width
of these nanoribbons are about 20–80 nm and 50–300 nm,
respectively, while their length usually reaches several millimeters
long. The products were further studied by transmission elec-
tron microscopy (TEM, H-800) and high-resolution transmission
electron microscopy (HRTEM, JEOL-2010). The TEM images
in Fig. 2D and 2E also show the characteristics of ribbon-like
morphologies, consistent with the FESEM observations. The inset
of Fig. 2E shows the electron diffraction (ED) pattern of a single
nanoribbon, which shows that the nanoribbon is a single crystal.
The HRTEM image in Fig. 2F also shows the good crystallinity
of the nanoribbons. The fringes (inset of Fig. 2F) are separated
particles could easily transfer to the surface of Bi
2
3
S nanoribbons
and react with them under the solvent–thermal conditions, while
the large particles showed less activity. Note that the CuCl particles
had a broad size distribution in the intermediate, resulting from
the grinding pre-treatment. In our experiments, thanks to the
inactivity of large CuCl particles, the added CuCl should be more
than three times the stoichiometric amount for the production
˚
of pure Cu S after completion of the reaction. The excess CuCl
2
by about 2.0 A, which agrees with the (220) lattice spacing of the
particles could be completely removed by diluted HCl.
Fig. 3 Morphologies of intermediate products prepared for 16 h. (A)
Panoramic image; (B) magnified image. The inset is the magnified image
of the surface of the nanoribbons.
Generally, the slow reaction rate facilitates control over the
chemical composition of the products. In the present case, the
solvent-assisted reaction was also found to be a slow one, though
◦
it was carried out at 120 C. The XRD patterns of the intermediate
Fig. 2 (A), (B) and (C) are FESEM images of Cu
different magnifications; (D) and (E) are the TEM images of Cu
nanoribbons. The inset of E is the ED pattern of a single ribbon; (F)
is a typical HRTEM image of Cu S nanoribbons.
2
S nanoribbons with
products obtained at t = 8 h, 16 h and 24 h, after the by-products
were washed leaving pure sulfide behind, are shown in Fig. 4A, 4B
and 4C, respectively. From the patterns, one can see that there is
2
S
2
1
5 0 | Dalton Trans., 2006, 149–151
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many faults and mismatches have appeared. However, note that the
dominant fringes at different regions can be indexed to different
compounds. For example, the marked places could be indexed to
the (−210) lattice spacing of Bi
of Cu S, respectively. The HRTEM observation of the products
obtained at t = 16 h and 24 h also showed similar results. The
above results show that the reaction of Bi and CuCl does not
2
S
3
and the (220) lattice spacing
2
2
S
3
happen synchronously at all regions, which confirmed the FESEM
observation that the thin CuCl particles did not cover the surface
of Bi
2
S
3
uniformly. Note that whether the reaction between Bi
2
S
3
and CuCl in ethanol definitely belongs to a solid–solid one is not
very clear, although the studies of the intermediates suggest that
it is. Further investigation of the detailed reaction process is still
underway.
Conclusion
Fig. 4 XRD patterns of the intermediate products prepared over different
reaction times. (A) 8 h; (B) 16 h; (C) 24 h. The peaks marked with * belong
In conclusion, we have developed a solution-phase template
to Cu
2 2 3 2 3
S while the others belong to Bi S . Note that Bi S has complicated
approach to synthesize Cu
nanoribbons could act as both template and reactant in the
reaction process. The as-prepared Cu S nanoribbons were well
2
S nanoribbons for the first time. Bi
2
S
3
peaks.
2
an obvious shift from Bi
2
S
3
(JCPDS 17–320) to Cu S (JCPDS 84–
2
characterized by XRD, FESEM, TEM and HRTEM, respectively.
The intermediate products were also investigated, showing that
1
770) upon reaction. The elemental analyses of these intermediate
products also determined that the content of Bi decreased along
with the reaction time while that of Cu increased. These results
show that the chemical compositions of the nanoribbons can be
rationally controlled via the solution-phase template approach.
different compositions of Bi
through controlling the reaction time.
2
S
3
and Cu S also could be obtained
2
Acknowledgements
Definitely, we obtained Cu
2
S/Bi
2
3
S nanoribbons with different
compositions in these intermediate products.
The intermediate products composed of Cu
This work is supported by the National Natural Science Founda-
tion of China.
2
S/Bi
2
3
S nanorib-
bons were also investigated by HRTEM. Typical HRTEM images
of the products obtained at t = 8 h are shown in Fig. 5. From
the HRTEM image with low magnification (Fig. 5A), one can
clearly see that the surface of the nanoribbons is very uneven,
revealing that the reaction did not synchronously happen at
References
1
2
J. T. Hu, T. W. Odom and C. M. Lieber, Acc. Chem. Res., 1999, 32, 435.
Y. N. Xia, P. D. Yang, Y. G. Sun, Y. Y. Wu, B. Mayers and B. Gates,
Adv. Mater., 2003, 15, 353.
the surface of the Bi
2
S
3
nanoribbons. Closer inspection of the
3 Z. W. Pan, Z. R. Dai and Z. L. Wang, Science, 2001, 291, 1947.
4 Z. L. Wang, Annu. Rev. Phys. Chem., 2004, 55, 159.
nanoribbons at different regions (Fig. 5A and 5B) shows that
5
6
Y. Ding, P. X. Gao and Z. L. Wang, J. Am. Chem. Soc., 2004, 126, 2066.
J. G. Yu, J. C. Yu, W. K. Ho, L. Wu and X. C. Wang, J. Am. Chem.
Soc., 2004, 126, 3422.
7
8
X. B. Cao, Y. Xie, S. Y. Zhang and F. Q. Li, Adv. Mater., 2004, 16, 649.
B. Zhang, C. B. Cao, X. Xiang and H. S. Zhu, Chem. Commun., 2004,
2
452.
C. B. Murray, C. R. Kagan and M. G. Bawendi, Science, 1995, 270,
335.
9
1
1
1
0 A. P. Alivisatos, Science, 1996, 271, 933.
1 V. Kilmov, P. H. Boilvar, H. Kurz, V. Karavanskii, V. Krasovskii and Y.
Korkishko, Appl. Phys. Lett., 1995, 67, 653.
1
1
2 T. H. Larsen, M. B. Sigman, A. Ghezelbash, R. C. Doty and B. A.
Korgel, J. Am. Chem. Soc., 2003, 125, 5638.
3 M. B. Sigman, A. Ghezelbash, T. Hanrath, A. E. Saunders, F. Lee and
B. A. Korgel, J. Am. Chem. Soc., 2003, 125, 16050.
Fig. 5 HRTEM images of the intermediate product obtained at t = 8 h.
1
1
4 S. H. Wang and S. H. Yang, Adv. Mater. Opt. Electron., 2000, 10, 39.
5 J. Chen, S. Z. Deng, N. S. Xu, S. H. Wang, X. G. Wen, S. H. Yang, C. L.
Yang, J. N. Wang and W. K. Ge, Appl. Phys. Lett., 2002, 80, 3620.
(
A) Typical image of a single nanoribbon; (B) magnified image showing
the dominant fringes of Bi
2
S
3
; (C) magnified image showing the dominant
fringes of Cu
bars.
2
S. Note that four fringes contained between the two white
16 Z. P. Liu, S. Peng, Q. Xie, Z. K. Hu, Y. Yang, S. Y. Zhang and Y. T.
Qian, Adv. Mater., 2003, 15, 936.
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Dalton Trans., 2006, 149–151 | 1 5 1