Shape-controlled synthesis of copper telluride micro/nanostructures via a simple electrochemical deposition route

Article abstract of DOI:10.1039/c4ce00999a

Shape-controllable synthesis of copper telluride micro/nanostructures has been successfully realized in air at room temperature by a simple galvanostatic electrodeposition route. By tuning experimental parameters such as the original Cu and Te sources, additives, deposition currents and media, copper telluride micro/nanostructures with various morphologies, including nanorod arrays, nanosphere-strewn copper telluride dendrites, copper telluride nanowires and star-like hexagonal copper telluride dendrites, were rapidly deposited in air at room temperature for 5 min. The final products were characterized by various means including X-ray diffraction, scanning electron microscopy, (high-resolution) transmission electron microscopy, and energy-dispersive spectrometry. The mechanisms of copper telluride production in various media are discussed. This journal is the Partner Organisations 2014.

Full text of DOI:10.1039/c4ce00999a

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Shape-controlled synthesis of copper telluride
micro/nanostructures via a simple electrochemical
deposition route
Cite this: CrystEngComm, 2014, 16,
869
7
*a
a
a
a
a
Received 13th May 2014,
Accepted 3rd July 2014
Yonghong Ni, Huying Zhang, Junjun Xi, Xuemei Wang, Yongmei Zhang,
a
b
b
Yanling Xiao, Xiang Ma and Jianming Hong
DOI: 10.1039/c4ce00999a
www.rsc.org/crystengcomm
Shape-controllable synthesis of copper telluride micro/
nanostructures has been successfully realized in air at room
temperature by a simple galvanostatic electrodeposition route. By
tuning experimental parameters such as the original Cu and Te
sources, additives, deposition currents and media, copper telluride
micro/nanostructures with various morphologies, including
nanorod arrays, nanosphere-strewn copper telluride dendrites,
copper telluride nanowires and star-like hexagonal copper
telluride dendrites, were rapidly deposited in air at room tempera-
ture for 5 min. The final products were characterized by various
means including X-ray diffraction, scanning electron microscopy,
synthesized by various methods. For example, Kumar
and Singh prepared Cu Te nanoparticles on a large scale
2
1
1
by employing an element-directed wet chemical route.
She et al. synthesized CuTe nanoribbons through a template-
free electrochemical route. Zhang et al. fabricated copper
telluride nanowires/nanorods in different media via a modified
1
2
7
hydrothermal method. Yang et al. designed a hydrothermal
reduction route to successfully prepare a series of non-
1
3
stoichiometric copper telluride nanocrystallites. Li et al.
reported the successful synthesis of nanocrystalline Cu Te
7
4
1
4
via a sonochemical approach or a solvothermal route. Sheet-
and ribbon-like Cu Te nanostructures were also obtained
through an amine-assisted solvothermal route.
group also successfully prepared dendritic Cu Te superstruc-
(
high-resolution) transmission electron microscopy, and energy-
7
4
15–17
dispersive spectrometry. The mechanisms of copper telluride
production in various media are discussed.
In 2011, our
7
4
3
tures constructed from spherical nanoparticles in HNO medium
via a simple electrochemical deposition route, employing
1
. Introduction
Cu(CH COO) and Na TeO as the reactants without the assis-
3
2
2
1
3
4
tance of any additive. However, the shape-controlled syn-
thesis of copper telluride through a simple electrodeposition
technology has not been reported in the literature to date.
In this paper, we employed simple electrochemical deposi-
tion routes to successfully realize the shape-controlled
synthesis of copper telluride micro/nanostructures. All depo-
sition processes were carried out in galvanostatic mode in
air at room temperature for 5 min. Copper telluride micro/
nanostructures with various shapes, including nanorod
arrays, nanosphere-strewn dendrites, nanowires, and star-like
hexagonal dendrites, were obtained by adjusting experimental
parameters such as the original Cu ion sources, additives, media,
and deposition currents. Also, the mechanisms of copper
telluride production in various systems are discussed.
Over the past two decades, copper tellurides have been receiv-
ing considerable attention due to their potential applications
in various devices such as solar cells, superionic conductors,
photodetectors, photothermal conversion, electroconductive
electrodes, microwave-shielding coatings, and optical data
1
–8
storage.
Also, copper tellurides are important for founda-
tional study owing to their large number of compositions
including stoichiometric CuTe, Cu Te , Cu Te , Cu Te ,
4
3
7
5
7
4
9
Cu
2
Te and nonstoichiometric Cu2−xTe.
Previous reports mainly focused on the thin-film materials
and bulk materials of copper tellurides.
4
,7,10
In recent years,
nanostructured copper tellurides, including nanoparticles,
nanorods, nanowires and nanoribbons, have been successfully
a
College of Chemistry and Materials Science, Key Laboratory of Functional Molecular
Solids of Education Ministry, Anhui Laboratory of Molecule-Based Materials,
Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University,
2
. Experimental section
1
Beijing East Road, Wuhu, 241000, PR China. E-mail: niyh@mail.ahnu.edu.cn;
All reagents and chemicals were analytically pure, purchased
from Shanghai Chemical Company and used without further
purification.
Fax: +86 553 3869303
b
Centres of Modern Analyses, Nanjing University, 23 Hankou Road, Nanjing,
210093, PR China
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2
.1 Shape-controlled synthesis of copper telluride
micro/nanostructures
In a typical experiment, a conventional three-electrode cell
is used, employing a Pt wire as the counter electrode, a
saturated Ag/AgCl electrode as the reference electrode, and a
2
Cu plate (99.99%, 1.0 × 1.0 cm ) as the working electrode.
To successfully obtain the products with various shapes,
different original electrolytes were prepared (see Table 1).
The electrodeposition experiments were conducted in galvanostatic
mode in air at room temperature for 5 min. The volumes of
all electrolytes were 30 mL.
2
.2 Characterization
Fig. 1 XRD patterns of the products deposited by galvanostatic
electrolysis in various systems for 5 min.
The X-ray diffraction (XRD) patterns of the electrodeposited
products were recorded on a Shimadzu XRD-6000 X-ray
diffractometer (Cu Kα radiation, λ = 0.154060 nm) at a
−
1
scanning rate of 0.02 s and a 2θ range of 10° to 80°. Field
emission scanning electron microscopy (SEM) images and
energy-dispersive spectra (EDS) of the final products were
taken on a Hitachi S-4800 field emission scanning electron
microscope at accelerating voltages of 5 and 15 kV,
respectively. For EDS analyses, small amounts of products
were removed from the Cu plate and fixed to a Ni substrate
with double-sided adhesive tape to avoid interference of the
Cu substrate. High-resolution transmission electron micros-
copy (HRTEM) images were recorded on a JEOL 2010 trans-
mission electron microscope at an accelerating voltage of
7 4
diffraction peaks can be indexed to the hexagonal Cu Te
form by comparison with the data for JCPDS card file
no. 65-2057 (see Fig. 1 (bottom)). Three weak peaks centred at
~26.5°, ~29.2° and ~48.6° can be attributed to the orthorhom-
bic Cu Te form (no. 42-1254), in good agreement with
4
3
1
8
our previous work. ICP-AES analyses showed that all
samples contained close contents of Cu Te and Cu Te . For
example, the final product consisted of 67.4% Cu Te and
7
4
4
3
7
4
32.6% Cu
4
Te
3
in samples 2 and 3, 67.1% Cu
7
Te
4
and 32.9%
Te in
Cu Te in sample 4, and 67.8% Cu
4
3
7
Te and 32.2% Cu
4
4
3
sample 5. In the standard data, moreover, the (012) peak is
far weaker than the (111) and (202) ones. However, the (202)
peak could not be clearly detected in the XRD pattern of
sample 2; simultaneously, the (012) peak exhibited a close
intensity to the (111) one. The above phenomena imply the
oriented growth of the final product. In sample 5, how-
ever, some diffraction peaks that were strong in samples 2–4
dramatically weakened or disappeared, i.e. the peaks located
at 20°–30° and the (203) one at 45.3°; simultaneously, some weak
peaks markedly increased, including the (003), (300), (103),
(031), (124), (232) and (242) ones. The above facts likewise show
the oriented growth of sample 5. To further analyze the com-
positions of samples 2–5, the EDS technique was employed.
EDS analyses of the four samples are shown in Fig. 2. Distinctly,
the four EDS spectra are similar except for their intensities.
2
00 kV. The content of Cu Te in the final product was
7 4
analyzed by inductively coupled plasma atomic emission
spectroscopy (ICP-AES, Optima 5300DV-ICP, Perkin-Elmer).
3
. Results and discussion
3
.1 Shape-controlled synthesis and characterization of copper
telluride micro/nanostructures
The XRD patterns of the products obtained under various
experimental conditions (see Table 1) are displayed in Fig. 1.
One can easily observe that samples 2, 3 and 4 exhibit similar
diffraction patterns but sample 5 does not; the diffraction peak
intensities gradually decreased from sample 2 to sample 4.
According to the XRD pattern of sample 2, most of the
Table 1 The original experimental parameters and the morphologies of the final products
Entry
1
Cu source
Te source
Na TeO
Surfactant
Medium
HNO
Complexant
pH
0.55
I/mA
Shape of the final product
Dendrites built up
of nanospheres
Nanorod arrays
a
2
CuAc
2
3
—
3
—
16
c
0
.5 mmol
0.5 mmol
Na TeO
mmol
Na TeO
mmol
TeO
0.5 mmol
Na TeO
0.5 mmol
2 mL, 4.8 M
HNO
3 mL, 3.6 M
HNO
b
2
3
4
5
Cu plate
2
3
SDBS
3
—
0.56
0.50
16
16
4
1
0.1 mmol
SDBS
0.1 mmol
—
Cu plate
2
3
3
Tartaric acid
1 mmol
—
Dendrites strewn
with nanospheres
Nanowires
1
3 mL, 3.6 M
KOH
5 mmol
CuSO
mmol
CuSO
mmol
4
2
11.65
11.48
2
4
2
3
—
3 2
NH ·H O
—
20
Star-like dendrites
1
25%, 12 mL
a
b
c
2 3 2
CuAc : Cu(CH COO) .
SDBS: sodium dodecylbenzenesulfonate. Ref. 18.
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Fig. 3 Electron micrographs of the product prepared from the system
2 3 3
containing 1.0 mmol of Na TeO , 3 mL of 3.6 M HNO 0.1 mmol of
SDBS at a deposition current of 16 mA for 5 min: (a) a lateral SEM
image (the inset is a planform) and (b) a typical TEM image. The inset
shown in (b) is an HRTEM image.
Fig. 2 EDS analyses of the products prepared by galvanostatic
electrolysis from various systems for 5 min.
The strong Cu and Te peaks can be easily observed, confirming
the formation of copper telluride. The C peaks in samples 2
and 3 are stronger than those in samples 4 and 5, which
could be attributed to the residual organic additives in
samples 2 and 3, such as SDBS and/or tartaric acid. Also, the
EDS spectra of samples 4 and 5 can be fully superimposed on
each other, indicating that they bear a similar chemical
composition. Furthermore, the gradual decrease of the peak
intensities in the XRD patterns from sample 2 to sample 4
could be related to the electrolytes. Based on the analyses of
Table 1, one can find that strong diffraction peaks can be
obtained in HNO media (e.g. samples 2 and 3) while in KOH
3
medium, the diffraction peaks weaken (sample 4). It is well
Fig. 4 Electron micrographs of the product prepared from the system
containing 1.0 mmol of Na TeO , 3 mL of 3.6 M HNO , 0.1 mmol of
2 3 3
2
+
known that Cu(OH)
and OH ions are mixed according to a 1 : 2 molar ratio, dra-
matically reducing the concentration of free Cu ions in the
electrolyte. In sample 4, Cu ions, TeO
2
precipitates can be formed when Cu
−
SDBS and 1 mmol of tartaric acid at a deposition current of 16 mA
for 5 min: (a) a representative low-magnification SEM image (the inset
is a high-resolution SEM image of the top of dendrites), (b) a high-
magnification SEM image of the stems, (c) a typical TEM image
(the inset is a SAED pattern) and (d) an HRTEM image of the stem with
a spherical nanoparticle.
2
+
2
+
2
and KOH completely
2
+
reacted to form Cu(OH) and K TeO . Thus, the free Cu ion
2
2
3
concentration was dramatically reduced. In sample 5, excess
2
+
ammonia was used. Thus, [Cu(NH
3
)
4
]
complex ions were
obtained, which also decreased the concentration of free
2
+
Cu
ions. However, different deposition currents were
employed in various systems. Therefore, different systems
have different deposition, nucleation and growth rates. As a
result, the final products deposited in different systems have
different crystallinities.
The morphologies of the products were observed by
SEM and TEM. Fig. 3–6 show the SEM and TEM images of
samples 2–5, respectively. Obviously, the morphologies of all
products are different. Sample 2 presents an array archi-
tecture built up of nanorods (see Fig. 3a). These nano-
rods are assembled from nearly spherical nanoparticles with
diameters from ~20 nm to ~80 nm; the lengths of nanorods
are ~1 μm. Although the orderly nanorod arrays have been
broken by ultrasound during the TEM sample preparation,
some rod-like structures built up of nanoparticles can still be
found (see Fig. 3b). The sizes of most nanoparticles range
from 20 to 40 nm, which are lower than those observed by
SEM. This implies that the larger, nearly spherical nano-
particles shown in Fig. 3a comprise smaller nanoparticles.
Fig. 5 Electron micrographs of the product prepared from the system
containing 2.0 mmol of CuSO , 0.5 mmol of TeO and 5 mmol of KOH
4 2
at a deposition current of 4 mA for 5 min: (a) a representative low-
magnification SEM image (the inset is a high-resolution SEM image)
and (b) a TEM image of nanowires (upper inset: an ED pattern; lower
inset: an HRTEM image).
Sample 3 is composed of abundant undergrowth-like
structures (see Fig. 4a and its inset). High-magnification
SEM images show that many spherical nanoparticles with a
diameter of ~30 nm are strewn on the stems (Fig. 4b) and
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pattern shown in the inset of Fig. 6d indicated the poly-
crystalline nature of the product. Distinctly, sample 4 had a
different growth environment from sample 5 although both
were deposited in basic systems.
3.2 Possible formation process
Based on the above results and Table 1, one can easily
conclude that copper telluride can be deposited in various
systems and that its morphology can be tuned by varying
experimental parameters including electrodeposition media,
surfactants and complexants, and deposition current. However,
the formation mechanisms of copper telluride should be dif-
1
8
ferent in various systems. According to our previous report,
in the acidic system where sample 1 was deposited, the forma-
tion of copper telluride underwent the following reactions:
Fig. 6 Electron micrographs of the product prepared from the system
2
+
−
+
Cu + e → Cu
(1)
(2)
(3)
(4)
containing 1.0 mmol of CuSO
4 2 3
, 0.5 mmol of Na TeO and 12 mL of
2
5% NH ·H O at a deposition current of 20 mA for 5 min: (a) a
3
2
2
−
−
+
2−
representative low-magnification SEM image, (b) a high-resolution
SEM image, (c) a planform of the top of dendrites and (d) a TEM image
TeO3 + 6e + 6H → Te + 3H O
2
(
upper left inset: an ED pattern).
+
2+
2−
6
Cu + Cu + 4Te → Cu
7
Te
4
+
2+
2−
that the thick stems are made up of many thin nano-
wires (see the inset in Fig. 4b). The above results are con-
firmed by TEM observations (see Fig. 4c). Moreover, the HRTEM
images depicted in the insets of Fig. 3b and 4d reveal good
crystallinities of samples 2 and 3, respectively. The distances
between the neighbouring planes were measured to be
2Cu + 2Cu + 3Te → Cu Te
4
3
Samples 2 and 3 were also deposited in HNO3 media.
Here, the Cu plate was used as the Cu source instead of Cu
ions and simultaneously additives were introduced. However,
2
+
2
+
Cu can be oxidized to Cu ions owing to the oxidation of
~
0
0.36 nm, which corresponds to the lattice spacing of
.361 nm of the (002) plane of Cu Te . According to Table 1,
HNO . Thus, samples 2 and 3 were also formed according to
3
7
4
the above reactions. The generated copper telluride gradually
nucleated and grew to form nanospheres. With the assis-
tance of additives, finally, nanospheres assembled into nano-
rod arrays (sample 2) or further grew into dendrites strewn
with nanospheres (sample 3).
samples 2 and 3 were prepared under the same deposition
conditions before and after the introduction of 1 mmol of
tartaric acid, respectively. Therefore, they should have similar
growth environments. It is well known that tartaric acid
has strong coordination ability to Cu ions. It is possible
that copper telluride nuclei were surrounded by tartaric acid
molecules, which limited the growth direction of copper
telluride. As a result, the shape of copper telluride was con-
verted from nanorod arrays to nanoparticle-strewn under-
growth-like microstructures.
Different from samples 2 and 3, samples 4 and 5 were
deposited in basic systems. Their growth environments should
be different from those in the acid ones. As shown in Fig. 5a,
sample 4 was composed of a large number of wrapped nano-
wires with diameters ranging from 40 to 60 nm. However,
these nanowires were not smooth. Some small nanoparticles
and short nanorods grew on their surfaces (see Fig. 5b). The
ED pattern and the HRTEM image confirmed the good crystal-
linity of the final product (see the insets in Fig. 5b). Here,
the distance between neighbouring stripes of sample 4 is
2
+
2+
−
In basic systems, however, Cu ions can react with OH
2
+
and NH
3
to form Cu(OH)
2
and [Cu(NH
3
)
4
]
ions, respectively.
2
+
In the current work, free Cu ions were converted into
Cu(OH) in the KOH system or into [Cu(NH ) ] complex ions
2
+
2
3 4
in the aqueous ammonia system, resulting in the decrease of
2
+
the Cu ion concentrations in these systems. Due to the reac-
2
−
tion between TeO and KOH, the Te source was TeO ions in
2 3
2
−
both systems. Here, different from acidic systems, Te ions
could be generated in alkali systems according to eqn (5):
2
−
−
2−
−
TeO
3
+ 6e + 3H
2
O → Te + 6OH
(5)
+
Simultaneously, Cu could still be produced according
2
+
to eqn (1) despite the low Cu ion concentrations in the
systems. Finally, copper telluride was formed according to
eqn (3) and (4). Since the produced nanocrystals had differ-
~
0.24 nm, which is very close to the lattice spacing of the
ent growth environments in KOH and NH
3
systems, the final
(
003) plane of Cu Te . Sample 5 presented dendritic hierarchi-
products presented different shapes and crystallinity.
7
4
cal microstructures (Fig. 6a and d). Each dendrite comprised
several subbranches, and each subbranch was made up of
smaller subbranches (Fig. 6b). All dendrites and subbranches
present six-petal structures (see Fig. 6c). However, the SAED
3
.3 Influencing factors
As mentioned in the previous text, copper telluride micro/
nanostructures with various shapes could be prepared by
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varying experimental parameters. In fact, the formation of
copper telluride with a certain shape is likewise affected by
various parameters. Here, we selected the preparation of
nanorod arrays as a case to investigate the influence of exper-
imental parameters on the morphology of the final product.
During the synthesis of nanorod arrays, when the Cu and Te
sources did not change, the main parameters included the type
and amount of surfactant, the type of acid and the amount
of nitric acid, the deposition current and the time. Among
these, the surfactant and nitric acid are two important
factors.
Fig.
8
SEM images of the products obtained under the same
conditions in the presence of different surfactants: (a) PVP and
(b) CTAB.
3
.3.1 The influence of the surfactant. When no surfactant
was used, the product consisted of abundant loose irregular
nanoparticles and some feather-like flakes under the same
experimental conditions (Fig. 7a). After 0.05 mmol of SDBS
was introduced into the system, the morphology of the
product markedly changed and thicket-like superstructures
with long leaves on the top were obtained (Fig. 7b). When
to their opposite charges. This would strongly affect the
morphology of the final product, which has been proven by
SEM observations (Fig. 7). Based on the results of SEM obser-
vations, SDBS could act as both a structure-directing agent
and a surfactant. At low SDBS amounts, e.g. 0.05 mmol, it
mainly acted as a structure-directing agent. Thus, thicket-like
superstructures with long leaves on the top were obtained
(Fig. 7b). With the increase in the amount of SDBS in the sys-
tem, however, the surfactant function could not be ignored.
When the above two roles cooperated, nanorod arrays assem-
bled from a large number of near-spherical nanoparticles
were obtained. In PVP molecules, some atoms such as N and
O have stronger coordination abilities. It is possible that copper
telluride nuclei were surrounded by PVP due to certain weak
interactions between N and Cu. As a result, flower-like super-
0
.1 mmol of SDBS was added, nanorod arrays assembled from
a large number of near-spherical nanoparticles were obtained
Fig. 3). Upon further increasing the amount of SDBS, the
(
nanorod arrays were always deposited. Fig. 7c and d show the
representative SEM images of the products obtained in the
presence of 0.2 mmol and 0.5 mmol of SDBS, respectively.
The above experiments indicate that high SDBS concentration
results in the formation of nanorod arrays. Furthermore,
when SDBS was replaced by other surfactants with the same
amount, such as polyvinylpyrrolidone (PVP) and cetyltrimethyl-
ammonium bromide (CTAB), SEM observations showed that
flower-like and feather-like superstructures were obtained
under the same experimental conditions, respectively (see
structures were deposited (Fig. 8a). However, CTAB is a
+
cationic surfactant, which would be far away from HTeO
2
ions in the present system owing to the repulsion between
like charges. Thus, the product was mainly composed of
feather-like flakes (Fig. 8b).
Fig. 8). No nanorod arrays were formed in the presence of the
+
above two surfactants. Generally, HTeO
2
ions are considered
3.3.2 The influence of HNO
also strongly affect the formation of nanorod arrays. When
HNO was not introduced into the system, no product was
deposited under the present deposition conditions. After
mL of 3.6 M HNO was added under the same deposition
3 3
. Furthermore, HNO could
to be the main existence fashion of original tellurium source
1
9
in diluted HNO
3
solution. When SDBS, an anion surfactant,
3
+
exists in the system, it could be attracted to HTeO
2
ions due
2
3
conditions long vine-shaped products were obtained (Fig. 9a,
the inset is a planform). When 3 mL of 3.6 M HNO was
employed, nanorod arrays were deposited (Fig. 3). Upon
further increasing the volume of 3.6 M HNO to 5 mL and
mL, nanorod arrays were still formed (Fig. 9b and c).
3
3
7
After addition of more than 7 mL of 3.6 M HNO , however,
3
the nanorod arrays changed, becoming loose and irregular.
Interestingly, when HNO
3
was replaced by H
with the same H ion concentration, the deposition reaction
did not occur, confirming that HNO is indispensable in the
formation of nanorod arrays. It is well known that HNO is
2 4 4
SO or HClO
+
3
3
an oxidative acid. It can oxidize copper atoms on the surface
of the Cu plate used as the Cu ion source. However, diluted
H SO or HClO is non-oxidative, thus copper atoms on the
2 4 4
surface of the Cu plate cannot be activated by them. There-
fore, different results are obtained.
3
.3.3 The influence of the deposition time. Fig. 10 shows
Fig. 7 SEM images of the final product obtained under the same
SEM images of the products deposited at various durations.
conditions with different amounts of SDBS in the system: (a) 0.0,
(
b) 0.05 mmol, (c) 0.2 mmol and (d) 0.5 mmol.
At the initial stage of deposition (e.g. 10 s), some sheet-like
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arrays were obtained with relatively uniform sizes (see Fig. 3).
If longer deposition durations were employed, e.g. 10 min,
the final product comprised a large number of undergrowths
of ~80 μm in length (Fig. 10f). The tops of the undergrowths
exhibited leaf-like structures which were constructed from a
large number of nanosheets (see the inset in Fig. 10f). The
above experimental facts clearly demonstrate that the forma-
tion of nanorod arrays derives from the vertically oriented
assembly/growth of the nanoparticle film deposited on the
+
Cu substrate. As mentioned in the previous text, HTeO2 ions
could be formed due to the reaction between Na TeO and
2
3
HNO
was rapidly generated, nucleated and grew into particle films
Fig. 10a and b). With the assistance of SDBS, freshly pro-
3
. At the deposition current of 16 mA, copper telluride
(
duced copper telluride nanoparticles ceaselessly grew on the
above particle film. Thus, nanorod arrays consisting of abun-
dant nanoparticles were finally obtained.
Fig. 9 SEM images of the products prepared under the same
deposition conditions from the system containing various volumes of
3
3.6 M HNO : (a) 2 mL, (b) 5 mL and (c) 7 mL.
Furthermore, experiments revealed that low or high depo-
sition currents did not lead to the formation of nanorod
arrays and that 16 mA is the optimum current.
4. Conclusions
In summary, shape-controllable syntheses of copper telluride
micro/nanostructures have been successfully realized via a
simple electrodeposition route in air at room temperature by
employing different electrodeposition media, additives and
deposition currents. All copper telluride micro/nano-
structures were obtained within 5 min. ICP-AES analyses
showed that all samples have similar contents of Cu
7 4
Te
and Cu Te . For samples 2 to 5, the content of Cu Te was
4
3
7
4
6
7.4%, 67.4%, 67.1% and 67.8%, respectively. Copper tellu-
ride dendrites constructed from spherical nanoparticles were
prepared at a deposition current of 16 mA using CuSO4,
2 3 3
Na TeO and diluted HNO as the original reactants without
1
8
the assistance of any additives. Under the same deposition
current, copper telluride nanorod arrays were deposited by
2 3 3
employing a Cu plate, Na TeO and diluted HNO as the origi-
nal reactants in the presence of sodium dodecylbenzene-
sulfonate while nanosphere-strewn copper telluride dendrites
were synthesized after a suitable amount of tartaric acid was
introduced to the above system. However, copper telluride
nanowires were prepared at a deposition current of 4 mA by
Fig. 10 SEM images of the products prepared under the same
experimental conditions at various deposition times: (a) 10 s, (b) 30 s,
4 2
utilizing CuSO , TeO and KOH as raw materials while star-like
(
c) 60 s, (d) 90 s, (e) 3 min and (f) 10 min.
copper telluride dendrites were obtained at a deposition cur-
rent of 20 mA, with CuSO , Na TeO and NH ·H O as the
4
2
3
3
2
3
electrolytes. Furthermore, experiments found that HNO and
SDBS are two indispensable factors for the formation of
copper telluride nanorod arrays.
particles were deposited on the Cu substrate (see Fig. 10a,
the inset is a SEM image of the Cu substrate.). After 30 s of
deposition, a film consisting of abundant nanoparticles was
obtained (Fig. 10b). Upon further prolonging the deposition
duration to 60 and 90 s, immature arrays started to appear
Acknowledgements
(
Fig. 10c and d). After 3 min, ordered arrays on the Cu sub-
strate were formed (Fig. 10e). When the deposition time was
prolonged to 5 min, compact and ordered Cu Te nanorod
The authors thank the National Natural Science Foundation
of China (21171005) and the Key Foundation of Chinese
Ministry of Education (210098) for fund support.
7
4
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1 P. Kumar and K. Singh, Cryst. Growth Des., 2009, 9, 3089.
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