Large scale synthesis of carbon hollow spheres from metal zinc powder and ethanol

Article abstract of DOI:10.1246/cl.2004.1346

A simple method was used to prepare carbon hollow spheres with average size of about 400 nm in diameter from metal zinc powder and ethanol. The FE-SEM and TEM images show that these carbon spheres have a ball-like and vessel-like morphology, all of which have smooth surfaces and a quite uniform diameter.

Full text of DOI:10.1246/cl.2004.1346

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Chemistry Letters Vol.33, No.10 (2004)
Large Scale Synthesis of Carbon Hollow Spheres from Metal Zinc Powder and Ethanol
ꢀ
Wu Zhang, Jianwei Liu, Zhen Huang, Dekun Ma, Jianbo Liang, and Yitai Qian
Structure research Laboratory and Department of Chemistry, University of Science and Technology of China,
Hefei, Anhui 230026, P. R. China
(Received July 13, 2004; CL-040829)
A simple method was used to prepare carbon hollow
not washed. Reflections in the figure can be indexed to hexago-
nal ZnO (JCPDS Card File, no.79-0205) and carbon. Figure 1b is
a typical XRD pattern of the as-prepared products washed with
dilute HCl aq solution and distilled water. The peak can be in-
dexed to the hexagonal carbon structure (002) plane. At the same
time, it is also observed that the position of the (002) peak shifts
to lower 2ꢂ angle. The d spacing of (002) plane is 3.4950 Aꢀ ,
which is larger than the reported value of graphite (d ¼
spheres with average size of about 400 nm in diameter from
metal zinc powder and ethanol. The FE-SEM and TEM images
show that these carbon spheres have a ball-like and vessel-like
morphology, all of which have smooth surfaces and a quite
uniform diameter.
ꢀ
Carbon materials have attracted much interest across the
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3:3756 A, JCPDS card, No.41-1487). This suggests that the
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world since the discovery of fullerenes, carbon nanotubes,
spacing between the sp carbon layers in the carbon hollow
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and close spherical carbon shells. In recent years, considerable
efforts have been made to fabricate different carbon structures
and to explore their applications. Carbon materials have a wide
range of applications including conductive and high-strength
spheres is increased. These investigations imply that the degree
of long-range order of these nanostructures is lower than that of
graphite. These results confirm that the reaction is similar to that
of magnesium and ethanol, in which metal powder reacts with
alcohol producing carbon, hydrogen, and metal oxide.
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composites, nanotweezers, gas storage media, semiconductor
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devices, and field emission displays. Among the various forms
of carbon, carbon hollow spheres are of increasing interest due to
their low density, large surface area, stability, and surface per-
meability. Previously, carbon spheres have been synthesized
by various methods.9
–12
The use of cheap non-toxic ethanol molecule as the carbon
source for the preparation of various carbon materials has long
been a goal for synthetic chemists. Recently, our group reported
large-scale synthesis of carbon nanotubes by an ethanol thermal
a
b
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0
20
30
40
/ deg
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60
70
2θ
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reduction process using Mg powder at 600 C, and hollow
carbon cones by the reduction of butyl alcohol with metal Mg
Figure 1. XRD patterns of the products: (a) not washed and
(b) after HCl treatment.
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powder at 500 C. Based on the results above, it would be
very interesting to study the reaction of other metal and alcohol
in solvothermal process.
Further evidence for the hexagonal carbon structure of the
sample can be obtained through Raman spectroscopy. Figure 2
shows that there are two strong peaks at 1336 and 1593 cm .
ꢂ1
The peak at 1593 cm corresponds to G mode of graphite and
ꢂ1
Herein, we report the preparation and characterization of
carbon hollow spheres by reduction of ethanol with zinc powder
2
ꢁ
is related to the vibration of sp -bonded carbon atoms in a 2-D
ꢂ1
at 550 C.
graphite layer. Compared with the G-band at 1580 cm for
In a typical procedure, the metal Zn powder (1 g; 99%),
and ethanol (40 mL) were mixed in a stainless steel autoclave
of 60-mL capacity. The autoclave was sealed and maintained
the graphitic carbons, the G-band of the products shifts towards
a higher wavenumber due to the less orderly arrangement of the
carbon atoms, which implys that the graphitization degree of
carbon spheres is not high, and this agrees well with the XRD
result. The peak at 1336 cm is attributed to a disorder Raman
D mode of graphite.
FE-SEM images for the as-prepared products were shown in
ꢁ
at 550 C for 12 h and then allowed to cool down to room
temperature. Obtained dark precipitate was collected and wash-
ed with absolute ethanol, dilute HCl aq solution and
distilled water in that order. The sample was then dried in vacu-
ꢂ1
ꢁ
um at 65 C for 6 h.
The phase purity of the as-synthesized products was exam-
ined by X-ray diffraction patterns (XRD) using Philips X’Pert
PRO SUPER X-ray diffractometer with Cu Kꢀ radiation (ꢁ ¼
ꢀ
:541874 A). The morphologies of the as-prepared products
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were examined with field-emission scanning electron microsco-
py (FE-SEM), transmission electron microscopy (TEM), and
high-resolution transmission electron microscopy (HRTEM)
using an accelerating voltage of 200 kV. Raman spectra were
measured on a LabRAM HR Raman spectrophotometer at an
excitation wavelength of 514.5 nm.
800
1000
1200
1400
1600
1800
2000
-
1
Wavenumber / cm
Figure 2. Room-temperature Raman spectrum of the as-
prepared sample.
Figure 1a shows the XRD pattern of the products that were
Copyright Ó 2004 The Chemical Society of Japan

Chemistry Letters Vol.33, No.10 (2004)
1347
sheets. The graphite sheets cover the zinc particles and form car-
bon spheres, in which some ethanol and H2 may be encapsulated.
In the newly formed carbon spheres, ethanol reacts with zinc
continuously, and the hollow carbon spheres can be formed after
the zinc is consumed. In addition, it is found that the reaction
temperatures played a critical role in the formation of these car-
ꢁ
bon spheres. When the reaction was conducted at 400 C, the
main products were amorphous carbon. When the reaction tem-
ꢁ
perature was at 550 C, carbon spheres were the main products.
ꢁ
Figure 3. FE-SEM image of as-prepared sample.
However, as the temperature was further increased to 600 C,
some carbon nanotubes could be observed in the as-synthesized
sample.
In summary, carbon hollow spheres and vessels have been
ꢁ
synthesized from metal zinc powder and ethanol at 550 C for
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2 h. According to the special morphology of hollow spheres, the
products have potential applications, such as catalyst carriers
and electronic devices.
This work is supported by the National Natural Science
Foundation of China and 973 Projects of China.
Figure 4. (a) TEM images of carbon hollow spheres and
vessels; (b) broken carbon hollow spheres and SAED pattern
of carbon hollow spheres (insert); (c) HRTEM image of the wall
of a carbon hollow sphere.
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Published on the web (Advance View) September 18, 2004; DOI 10.1246/cl.2004.1346