ISSN 0020-1685, Inorganic Materials, 2007, Vol. 43, No. 9, pp. 945–950. © Pleiades Publishing, Inc., 2007.
Original Russian Text © A.G. Kudashov, L.G. Bulusheva, A.V. Okotrub, O.G. Abrosimov, Yu.V. Shubin, L.I. Yudanova, N.F. Yudanov, 2007, published in Neorganicheskie Materi-
aly, 2007, Vol. 43, No. 9, pp. 1056–1061.
Synthesis of CNx Nanotubes Using Catalysts Prepared
from Zinc and Nickel Bimaleates
a
a
a
b
A. G. Kudashov , L. G. Bulusheva , A. V. Okotrub , O. G. Abrosimov ,
a
a
a
Yu. V. Shubin , L. I. Yudanova , and N. F. Yudanov
a Nikolaev Institute of Inorganic Chemistry, Siberian Division,
Russian Academy of Sciences, pr. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia
b Boreskov Institute of Catalysis, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 5, Novosibirsk, 630090 Russia
e-mail: bul@che.nsk.su
Received October 24, 2006
Abstract—Nitrogen-containing carbon nanotubes have been prepared via acetonitrile (CH3CN) pyrolysis at
850°C catalyzed by nanoparticles produced by the thermal decomposition of zinc and nickel bimaleates and
their solid solutions. The synthesized samples have been characterized by transmission electron microscopy,
x-ray diffraction, and x-ray photoelectron spectroscopy. The results demonstrate that increasing the zinc content
of catalyst nanoparticles reduces the yield of carbon nanotubes and increases the nitrogen content of the mate-
rial. The high synthesis temperature gives rise to zinc vaporization, which influences the growth process,
increasing the nanotube diameter, reducing the wall thickness, and lowering the structural perfection of the
graphite layers.
DOI: 10.1134/S0020168507090063
INTRODUCTION
EXPERIMENTAL
To synthesize solid solutions, nickel and zinc
bimaleates in the molar ratio 7 : 3, 1 : 1, or 3 : 7 were
dissolved in water, and the solutions were then evapo-
rated to dryness at room temperature. Carbon nano-
tubes were synthesized as described elsewhere [6] in a
32-mm-diameter tubular quartz reactor mounted in a
low-gradient three-zone electrical furnace with a heat-
ing zone ~40 cm in length. The reactor was equipped
with temperature and flow controllers. After mounting
a ceramic boat containing bimaleate powder in the cold
zone of the reactor, it was pumped down, filled with
argon, and heated. Next, the boat was introduced into
the zone heated to 850°ë. After 10 min, acetonitrile
vapor was introduced into the reactor. In our experi-
ments, the flow rate of argon was maintained constant
at 500 cm3/min, and the synthesis time was 1 h.
Transition-metal (Ni, Co, Fe, Mn, and Zn) bimale-
ates are isostructural with each other [1, 2], which
offers the possibility of preparing continuous series of
solid solutions between these compounds. The bimale-
ates decompose at relatively low temperatures
(~450°ë) to form polymer-matrix composites contain-
ing metallic particles ~5 nm in size [3]. Such nanopar-
ticles are capable of catalyzing the growth of carbon
nanotubes via chemical vapor deposition, and their
composition is determined by the ratio of the metals in
the bimaleate solid solution. Combining two or more
metals in a particle may have a significant effect on the
growth kinetics of carbon nanotubes, determining their
structure [4]. Recent work [5] has shown that, among
NixCo1 – x catalysts, Ni0.5Co0.5 nanoparticles ensure the
highest content of twofold-coordinated (pyridine-like)
nitrogen in CNx nanotubes prepared via decomposition
of acetonitrile vapor.
The structure and nitrogen content of the samples
were determined by transmission electron microscopy
(TEM), x-ray diffraction (XRD), and x-ray photoelec-
tron spectroscopy (XPS).
In this paper, we describe the synthesis of nitrogen-
containing carbon materials using nanoparticles pre-
pared from nickel and zinc bimaleates and their solid
solutions. Since Zn is the most volatile transition metal,
Zn removal from bimetallic particles during the synthe-
sis of carbon nanotubes might reduce the particle size
of the catalyst and, accordingly, the diameter of the
forming nanotubes.
TEM images of the synthesized particles were
obtained on JEOL JEM-100 CX and JEM-2010 instru-
ments. TEM specimens were prepared on colloidal car-
bon substrates via sonication of suspended powder.
XRD measurements were made with a DRON–
SEIFERT-RM4 powder diffractometer (CuKα radia-
tion, diffracted-beam graphite monochromator, scintil-
lation detector, multichannel pulse-height analyzer).
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