Single crystal tin nano-rod arrays electrodeposited by a soft template

Article abstract of DOI:10.1039/b509818a

Single crystal tin nano-rod arrays were fabricated by the electrodeposition method when amphiphilic triblock copolymer P123 was used as a soft template at a concentration much lower than that for forming a liquid crystalline phase. The Royal Society of Chemistry 2005.

Full text of DOI:10.1039/b509818a

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Single crystal tin nano-rod arrays electrodeposited by a soft template
Qin Zhou,* Xiaoying Liu, Yaomin Zhao, Nengqin Jia, Ling Liu, Manming Yan and Zhiyu Jiang*
Received (in Cambridge, UK) 11th July 2005, Accepted 16th August 2005
First published as an Advance Article on the web 8th September 2005
DOI: 10.1039/b509818a
Single crystal tin nano-rod arrays were fabricated by the
electrodeposition method when amphiphilic triblock copolymer
P123 was used as a soft template at a concentration much
lower than that for forming a liquid crystalline phase.
ethanol in order to remove the surfactant. The electrode was
subsequently dried in air. The microstructures of the samples were
characterized by X-ray diffraction (XRD; Bruker D8 Advance
X-ray diffractometer, Cu-Ka radiation at 40 kV and 40 mA),
scanning electron microscopy (SEM; Philips XL30 at 30kV) fitted
with an energy dispersive X-ray spectroscopy (EDX) and trans-
mission electron microscopy (TEM; JEOL JEM 2011 at 200 kV).
The effect of experimental conditions on the growth of the
plating tins was carefully studied. The electroplating solution
Metal nano-wires have been studied for their important roles as
active components and/or interconnectors in fabricating nano scale
electronic or optoelectronic devices. It has been known that
electrodeposition is an efficient and ready technique for preparing
metal nano-fibers by employing hard templates such as meso-
4 2 4
consisted of water, ethanol, SnSO , H SO and copolymer P123. It
1
2,3
4,5
porous silicas, alumina templates, polycarbonate membranes
was found that in order to obtain tin nano-rod arrays, an aging
process for the electroplating solution was necessary before adding
the P123. During the aging period, a very small amount of pale
6,7
and carbon nanotubes. Although the use of physical templates
may have the advantages of predefined 1D morphology and
controllable wire diameters, there are also a number of intrinsic
shortcomings or limitations. For example, it is very difficult to
prepare single crystal nano-rods using hard templating methods.
There is also another method of obtaining nano-metal particles:
using soft templates such as lyotropic liquid crystalline phase
yellow-white precipitate (SnO ) was observed, which might be
2
produced via an oxidation reaction by the oxygen in the air. Some
2+
4+
Sn ions were oxidized to Sn as reported by Donaldson and
12
4+
Moser. The trace amount of Sn may influence the electro-
chemical deposition process strongly. The existence of P123 in the
electroplating bath is also very important to obtain tin nano-rod
arrays. Fig. 1 shows the morphologies of tin thin films deposited
from electroplating solution with or without P123 for 60 min at
8,9
materials. However, there are very few reports on the electro-
chemical synthesis of nano-rod arrays of tin though mesoporous
1
0
tin has been synthesized by using C18EO10 as a surfactant. In this
communication, we report the preparation of single crystal tin
nano-rod arrays by the electrochemical deposition method when
amphiphilic triblock poly(ethylene oxide)-b-poly(propylene oxide)-
b-poly(ethylene oxide) copolymer (EO20PO70EO20, P123) is used
as a soft template at a concentration much lower than that
required for forming a liquid crystalline phase. Comparison of the
structure with those prepared without P123, shows that the
presence of amphiphilic triblock copolymer P123 results in
fundamental changes in the microstructures of the electrodeposited
tin. The tin with a 1D nanostructure is of particular significance
because the unique morphology bears several important features.
Due to their array structure, tin nano-rods can be used as novel
cathodes of electron emitters for field electron emission applica-
22
current density of 3.2 mA cm at different temperatures. At a
temperature of 30 uC, the electrodeposited tin is in the form of
cuboid rods (Fig. 1a), which are perpendicular to the substrate.
The edge of the cross section is about 1–3 mm. But when the
deposition temperature was tuned to 40 uC, large domain tin nano-
rod arrays were formed as shown in Fig. 1b. It looks just like the
micro sized tin cuboid rods, as observed in Fig. 1a, are divided into
many uniform tin nano-rods. The diameter of the nano-rods is
11
+
tions and can shorten the Li diffusion pathway and release the
pressure induced by volume expansion upon lithium insertion
from the viewpoint of high specific surface area and pore volume.
A typical electroplating solution was prepared as follows: 15.87 g
of 0.15 M SnSO and 0.6 M H SO solution were mixed with
4
2
4
12.5 g ethanol solution of P123 (0.033 g P123 per ml ethanol). The
mixed solution underwent magnetic stirring for 1 h until the
solution became as turbid as milk. An electrolysis copper and a
cast tin plate were used as the cathode and anode, respectively. The
electrodeposition was conducted using a galvanostatic electro-
plating circuit. After deposition, the electrode was washed with
Department of Chemistry, and Shanghai Key Laboratory of Molecular
Catalysis and Innovative Materials, Fudan University, Shanghai,
P. R. China. E-mail: 021022037@fudan.edu.cn; zyjiang@fudan.ac.cn;
Fax: 86-21-65641740; Tel: 86-21-65642404
Fig. 1 SEM images and SAED patterns of tin electrodeposited from
solutions with P123, at 30 uC (a), 40 uC (b), 50 uC (c), and without P123 at
30 uC (d), for 60 min.
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Chem. Commun., 2005, 4941–4942 | 4941

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the amphiphilic species P123 tends to suppress the growth rate of
the other planes more than that of the {100} planes, leading to the
preferential growth rate, which is of essential importance for the
growth of 1D nano-materials. A similar special characteristic of
the surfactant was also observed for the chemical synthesis of gold
and silver nanoparticles using poly(vinylpyrrolidone) (PVP) as a
13
surface active additive by Xia.
We also investigated the relationship between the morphology
of tin and various experimental parameters including electro-
deposition time, the distance d between the two electrodes,
and current density. At 30 uC and a fixed current density of
2
2
3
.2 mA cm , we found that the morphologies of the tin nano-
rods at electrodeposition times of 30, 60, 90, 120 and 180 min
were similar to each other but that uniformity decreased as the
deposition time increased. The electrodeposited tin was the same as
that obtained without P123 under similar conditions when the
distance d increased to 5 cm. When changing the current density,
various tin nano-rods with different dimensions could be obtained
Fig. 2 XRD patterns of tin samples electrodeposited from solutions with
P123 at 30 uC (a), 40 uC (b) and 50 uC (c), and without P123 at 30 uC (d).
about 140 nm. However, with the temperature increasing to 50 uC,
the tin nano-rods became thinner and more irregular with a
diameter of about 120 nm (Fig. 1c). For comparison purposes, we
also tried the deposition of tin at 30 uC from a similar electrolyte
but without surfactant P123. The electrodeposited tin film shows a
rough granular structure as shown in Fig. 1d, and no tin nano-rods
can be observed.
22
with current densities higher than 3.2 mA cm . These phenomena
could be explained by the influence of the electric field on the
orientation of the P123 micelles in the liquid phase and at the
14
surface of the electrode.
In brief, well ordered single crystal tin nano-rod arrays have
been prepared via electrodeposition by using P123 as a soft
Selected area electron diffraction (SAED) patterns (inset in
Fig. 1) show that the tin nano-rods prepared with P123 at 30, 40
and 50 uC are in a single crystalline structure. The diffraction
pattern doesn’t change as the electron beam scans across individual
rods, suggesting that these tin nano-rods are single crystalline with
the same lattice structure. However, SAED patterns also show that
without P123 the electrodeposited tin is in polycrystalline structure,
further suggesting that the copolymer P123 plays a significant
role in the formation of the single-crystalline structure. The single
crystalline structure of tin nano-rods was further confirmed by
high-resolution TEM image (not shown here).
2
template. The precipitate of SnO and P123 are suggested to be
essential for the growth of the tin nano-rods. Due to the defined
morphology and crystal planes, tin nano-rods can be employed as
electrodes for various applications such as in the field of batteries
and field emission devices.
This work is supported by the Natural Science Foundation of
China (NSFC No.20333040).
Notes and references
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electrodeposited with P123 at temperatures of 30, 40 and 50 uC are
presented as curves a–c in Fig. 2, respectively. Curve d is the one
for the sample electrodeposited without P123 at a temperature of
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30 uC. The peaks can be assigned to the diffraction from (200),
(101), (220), (211) and (112) crystal planes of tetragonal tin as
labelled on the curves. For curve b, using Bragg’s equation,
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the lattice interplanar d-spacing constants for those planes are
˚
calculated as 2.90, 2.78, 2.08, 2.01, and 1.48 A respectively, which
7
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are in agreement with the report of Powder Diffraction Standards
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noting that the intensity ratios between the (200) and (101) peaks,
and between the (200) and (112) diffraction peaks of the tin nano-
rods (2.12 and 6.17 for curve b, 2.87 and 8.18 for curve c,
respectively) are much higher than those for the corresponding
bulk materials (1.25 and 4.17 respectively, JCPD 01-0926). This
may suggest that the {100} planes are the most abundant planes of
the single crystalline tin nano-rod samples. It can be proposed that
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This journal is ß The Royal Society of Chemistry 2005