Large-scale and catalyst-free synthesis of zinc nanotubes and nanowires

Article abstract of DOI:10.1016/j.ssc.2004.07.001

Metallic zinc one-dimensional materials including nanotubes and nanowires were synthesized on a large scale by a simple method. The process was both catalyst and template free. The resulting Zn nanotubes and Zn nanowires were characterized and confirmed by means of X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The growth of Zn nanotubes was reported for the first time.

Full text of DOI:10.1016/j.ssc.2004.07.001

Solid State Communications 131 (2004) 769–772
www.elsevier.com/locate/ssc
Large-scale and catalyst-free synthesis of zinc nanotubes
and nanowires
a,b,* a
Jianye Li
, Xiaolong Chen
a
Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100080,
People’s Republic of China
b
Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
Received 30 November 2003; received in revised form 26 June 2004; accepted 1 July 2004 by T.T.M. Palstra
Available online 29 July 2004
Abstract
Metallic zinc one-dimensional materials including nanotubes and nanowires were synthesized on a large scale by a simple
method. The process was both catalyst and template free. The resulting Zn nanotubes and Zn nanowires were characterized and
confirmed by means of X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy,
and transmission electron microscopy. The growth of Zn nanotubes was reported for the first time.
q 2004 Elsevier Ltd. All rights reserved.
PACS: 61.46.Cw; 68.65Cg; 81.15
Keywords: A. Metals; A. Nanostructures; B. Nanofabrications
1
. Introduction
large-scale synthesis of one-dimensional Zn materials
including nanotubes and nanowires by a very simple and
catalyst-free process. The successful fabrication of Zn
nanotubes will open up the possibility of complete
investigation of one-dimensional metal materials.
The synthesis of one-dimensional metal materials has
stimulated intensive research activities because of their
potential use as both active components and interconnects in
fabricating nanoscale electronic, photonic, and sensing
devices [1,2]. Up to now, considerable effort has been
focused on the fabrication of metal one-dimensional
materials and some metal nanotubes or nanowires such as
Au [3–8], Ag [9–12], Cu [13], Fe [14], Co [15], Ni [16,17],
Pd [18], Bi [19], W [20] etc. have been successfully
synthesized. Recently, zinc nanowires [21] and nanosheets
2
. Experimental section
The reaction we used to synthesize zinc one-dimensional
materials can be expressed as:
[
22] were synthesized. However, to the best of our
ZnO CNH3 /Zn CN2 CH2O
knowledge, there has been no report about the fabrication
of Zinc nanotubes so far. In this report, we describe the
The system we used is similar to that designed to grow
ZnO nanorods [23]. The preparation of the Zn nanotubes
and nanowires was carried out in a horizontal quartz tube
inside a conventional tube furnace. The length of the quartz
tube is 110 cm. No catalysts and templates are needed for
the growth of zinc one-dimensional materials by this
method.
*
Corresponding author. Department of Chemistry, Duke Univer-
sity, Gross Chemical Building, Durham, North Carolina 27708,
USA. Tel./fax: C1-919-660-1605.
E-mail address: jyli@duke.edu (J. Li).
0038-1098/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ssc.2004.07.001

770
J. Li, X. Chen / Solid State Communications 131 (2004) 769–772
Hexagonal zinc oxide powder with a purity of more than
9.9% was treated by a mechanical deformation process
24] firstly, which was carried out in a rolling laboratory ball
lattice constants aZ0.2665 nm and cZ0.4947 nm [25]. The
9
strong intensities of the zinc diffraction peaks relative to the
background signal indicated that the resulting black layer
had high purity of the hexagonal Zn phase.
[
mill using hardened agate balls and a nylon cell for 28 h.
Then the as-milled ZnO powders were loaded into the center
of the horizontal quartz glass tube. Before heating, the
quartz tube was pumped, and then filled with inert gas argon.
Fig. 2 is the FESEM images of the as-synthesized
products and it can be seen from Fig. 2 that the product
consists of nanotubes and nanowires. Most of the nanotubes
and nanowires have diameters in the range of about 60–
100 nm, and the length from several to tens mm. Inset of Fig.
2 is a FESEM image mainly consists of Zn nanotubes, and
from it the openings of the nanotubes can be seen.
After that, the quartz tube was heated under the flow of
3
argon of about 100 cm /min. At 860 8C, a flow of NH
3
about
3
5 cm /min was switched on, and the purity of the ammonia
2
was better than 99.99%. When 1060 8C was reached, the
temperature was kept constant for 90 min under the flow of
TEM observed results of the Zn one-dimensional
materials are shown in Fig. 3 and the TEM image
demonstrates the samples composed of Zn nanotubes and
nanowires. The TEM images also indicate that the diameters
of the Zn nanotubes and nanowires in the range of about 60–
100 nm. Inset of Fig.3 is the TEM image of a section of a
zinc nanotube with a diameter of about 60 nm.
3
NH . Then the power was switched off and the furnace was
allowed to cool to the room temperature naturally. After
pulling out the quartz glass tube from the furnace, we found
that the original as-milled ZnO powders were disappeared
and there was a black layer of wool-like products on the wall
close to the in-gate of the quartz tube.
The structure and composition of the black layer
products was characterized by X-ray diffraction (XRD)
The successful growth of Zn nanotubes and nanowire
were further confirmed by the EDX measurements. Fig. 4a
is the EDX spectrum of the tip (opening) of a nanotube with
a diameter of about 100 nm, and Fig. 4b is the EDX
spectrum of a nanowire with a diameter of about 90 nm. The
EDX results indicate unambiguously that both the nano-
tubes and nanowires are composed of only zinc element, and
verifying the above XRD results.
(
Rigaku D/max-2400 X-ray diffractometer with Cu Ka
radiation), field emission scanning electron microscopy
FESEM) equipped with energy dispersive X-ray (EDX)
(
spectroscopy (Hitachi S-4200), and transmission electron
microscopy (TEM) (Philips CM-12).
Vapor–liquid–solid (VLS) growth is common for the
formation of nanowires and nanotubes, in which liquid
catalyst (a liquid metal cluster of Au, Fe, Co, or Ni etc.) acts
as the energetically favored site for absorption of gas-phase
reactants [26]. In the present case, however, the VLS
mechanism seems not suitable to explain the growth of the
Zn one-dimensional materials. This is because there is no
catalyst used in the growing process and also only element
3
. Results and discussion
XRD measurements were made on the bulk samples and
to assess the overall crystal structure and phase purity of the
product. Fig.1 shows a typical powder XRD pattern of the
resulting products and all diffraction peaks shown in Fig.1
correspond to (002), (100), (101), (102), (103), (110), and
(004) of hexagonal Zn. The positions of the XRD peaks
show good agreement with those of the hexagonal Zn with
Fig. 1. Room temperature powder XRD pattern (Cu Ka radiation) of
the synthesized zinc one-dimensional materials. The (hkl) values of
the hexagonal Zn are specified at the diffraction peaks.
Fig. 2. FESEM images of zinc one-dimensional materials including
nanotubes and nanowires. Inset of Fig.2 is a FESEM image from
which the openings of the zinc nanotubes can be seen.

J. Li, X. Chen / Solid State Communications 131 (2004) 769–772
. Conclusion
In summary, the work presented here has demonstrated a
771
4
simple method to grow metallic zinc one-dimensional
materials including nanotubes and nanowires on a large
scale. The process was both catalyst and template free, and
the Zn one-dimensional materials were synthesized by a
reaction of as-milled ZnO powders and ammonia at
1
060 8C. The resulting Zn nanotubes and nanowires were
characterized and confirmed by means of XRD, FESEM,
TEM and EDX. Most of the nanotubes and nanowires have
diameters in the range of about 60–100 nm and a length
from several to tens microns. The successful growth of Zn
nanotubes was reported for the first time and it will open up
the possibility to investigate one-dimensional metal
materials completely.
Fig. 3. TEM images of zinc nanotubes and nanowires. Inset of Fig. 3
is a TEM image of a section of a zinc nanotube with a diameter of
about 60 nm.
Zn exists in the tip of the Zn nanowires and nanotubes. We
think the growth of the Zn one-dimensional materials via a
vapor–solid (VS) mechanism [27]: at the center of the
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