Preparation of NiO nanoparticles and their catalytic activity in the thermal decomposition of ammonium perchlorate

Article abstract of DOI:10.1016/j.tca.2005.06.027

NiO nanoparticles with an average size of 10 nm were prepared by a solid-state reaction using nickel acetate and sodium hydroxide as the raw materials and the Tween 80 as dispersant. The reaction was studied by DTA, TG, XRD and FTIR. The size and morphology of NiO nanoparticles were characterized by TEM. The catalytic effect of the NiO nanoparticles for thermal decomposition of ammonium perchlorate (AP) was investigated by DTA and TG. The catalytic performance of NiO nanoparticles is superior to that of bulk NiO particles. Adding 2% of NiO nanoparticles to AP decreases the decomposition temperature by 93 °C and increases the heat of decomposition from 590 to 1490 J g ^-1.

Full text of DOI:10.1016/j.tca.2005.06.027

Thermochimica Acta 437 (2005) 106–109
Preparation of NiO nanoparticles and their catalytic activity
in the thermal decomposition of ammonium perchlorate
Yanping Wang, Junwu Zhu, Xujie Yang, Lude Lu∗, Xin Wang
Materials Chemistry Laboratory, Nanjing University of Science and Technology, Nanjing 210094, China
Received 9 March 2005; received in revised form 17 June 2005; accepted 17 June 2005
Abstract
NiO nanoparticles with an average size of 10 nm were prepared by a solid-state reaction using nickel acetate and sodium hydroxide as the
raw materials and the Tween 80 as dispersant. The reaction was studied by DTA, TG, XRD and FTIR. The size and morphology of NiO
nanoparticles were characterized by TEM. The catalytic effect of the NiO nanoparticles for thermal decomposition of ammonium perchlorate
(AP) was investigated by DTA and TG. The catalytic performance of NiO nanoparticles is superior to that of bulk NiO particles. Adding 2% of
NiO nanoparticles to AP decreases the decomposition temperature by 93 ◦C and increases the heat of decomposition from 590 to 1490 J g−1
© 2005 Elsevier B.V. All rights reserved.
.
Keywords: NiO nanoparticles; Solid-state reaction; Ammonium perchlorate; Catalytic performance; Thermal decomposition
1. Introduction
metal oxides in the thermal decomposition of AP have been
reported [13–15]; nanometer-scale Cu2O, CuO and Fe2O3
as catalysts in the thermal decomposition of AP have been
reported [16–18]. Use of NiO and nanometer-scale NiO have
not been reported for this use. This paper describes the prepa-
ration of ∼10 nm NiO nanoparticles by solid-state reaction
and the role of NiO nanoparticles as a catalyst in thermal
decomposition of AP.
Nickel oxide (NiO) has received a considerable amount
of attention in recent years for its catalytic, electronic and
magnetic properties [1–3]. Nanometer-sized NiO is expected
to possess many better properties than those of bulk NiO
[4–7]. Carnes et al. [5] reported that NiO nanoparticles are
much more effective catalysts than commercial NiO powder
for catalytic reduction of carbon dioxide to methanol.
There are many different methods reported for the syn-
thesis of nanometer-sized nickel oxide [8–12], Among these
methods, the solid-state reaction exhibits many advantages,
no need for solvent, high yield, low energy consumption and
simple reaction technology. In this work, the preparation of
NiO nanoparticles was carried out via solid-state reaction of
Ni(OAc)2·4H2O and NaOH with Tween 80 as dispersant.
Ammonium perchlorate (AP) is the most common oxi-
dizer in composite solid propellants. The thermal decom-
position characteristics influence the combustion behavior
of the propellant [13]. The catalytic activities of transition
2. Experimental
2.1. Materials
Bulk NiO was spectrograde and other reagents were ana-
lytical grade chemicals. All were obtained from the Shanghai
chemical factory; Bulk NiO, NiO nanoparticles and AP were
mixed in 2:98 (wt%) respectively to prepare the samples for
the thermal analyses experiment.
2.2. Preparation of NiO nanoparticles
∗
NiO nanoparticles were prepared by grinding a stoi-
Corresponding author. Tel.: +86 25 8431 5054; fax: +86 25 84315 5054.
E-mail address: njwangyp@yahoo.com.cn (L. Lu).
chiometric amount of Ni(OAc)2·4H2O with NaOH and the
0040-6031/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.tca.2005.06.027

Y. Wang et al. / Thermochimica Acta 437 (2005) 106–109
107
appropriate amount of Tween 80 in an agate mortar at room
temperature for about half an hour. Then the products were
washed with distilled water, treated in an ultrasonic bath with
absolute ethanol and centrifuged. After that, the samples
were dried in desiccators at 80 ◦C for 4 h, a light green
powder was obtained which was then sintered at 400 ◦C for
2 h.
2.3. Instrumentation
X-ray diffraction (XRD) was carried out on a Bruker D8
Advance X-ray diffraction instrument (Cu K␣), the diffrac-
tion angle (2θ) from 25 to 80◦ was scanned. Transmission
electron microscopy (TEM) images were taken with a JEM-
200CX electron microscope, the sample was dispersed in
aqueous ethanol by ultrasonic stirring. FTIR spectra were
recorded from 400 to 4000 cm−1with a Bruker vector-22
Fourier transform infrared using the KBr pellet technique.
Shimadzu DTA-50 and Beijing WCT-2A thermal analyzers
were used at a heating rate of 20 ◦C/min in N2 atmosphere
over the range 20–500 ◦C with Al2O3 as reference.
Fig. 1. XRD pattern of: (a) as-prepared product; (b) precursors.
The NiO product was characterized by XRD, TEM and
FTIR. The XRD measurement (Fig. 1a) shows the product is
single-phase NiO with a cubic structure, the diffraction data
are in good agreement with JCPDS card of NiO (JCPDS no.:
01-1239), No impure peaks are observed in the XRD pattern.
The average particle size was ∼10 nm determined from the
XRD pattern parameters of the NiO powder according to
the Scherrer equation [19]. The TEM image in Fig. 2 verifies
this result and shows a homogenous particle distribution. The
diffuse nature of the electron diffraction pattern is attributed
to the contribution from the disordered grain boundary.
Fig. 3 shows the FTIR spectrum of the NiO product and
bulk NiO. The Ni–O band appears at 482 cm−1. In Fig. 3a,
the Ni–O has an absorption band at 437 cm−1[20] which
is red-shifted about 45 cm−1 compared with Fig. 3b, this
is caused by the nanometer-scale surface properties. Based
on the XRD, TEM and FTIR, the NiO nanoparticles were
obtained.
3. Results and discussion
3.1. The feasibility of solid-state reaction
Ni(OAc)2·4H2O reacts with NaOH during the process of
grinding. A black powder was obtained after the precursor
was sintered at 400 V for 2 h.
TG and DTA measurements were performed to study the
thermal behavior of the precursor. The weight loss starts
from room temperature, and there is a sharp weight loss
between 230 and 300 ◦C due to the decomposition of hydrox-
ide phase to NiO. DTA shows two endothermic peaks, a
weak endothermic peak at ∼75 ◦C associated with the loss of
physically absorbed water and a strong endothermic peak at
∼270 ◦C caused by dehydration of Ni(OH)2 [11]. The theo-
retical weight loss for the formation of NiO from the Ni(OH)2
is 19.4% while experimental value is about 30% which shows
there is some water and Tween not completely removed in
washing and drying.
3.2. Catalytic effect
The DTA curves for pure AP, AP in presence of bulk NiO
and AP in presence of NiO nanoparticles are shown in Fig. 4.
Fig. 2. TEM images and ED pattern of the NiO nanoparticles.

108
Y. Wang et al. / Thermochimica Acta 437 (2005) 106–109
Fig. 5. TG curves for: (a) AP + NiO nanoparticles; (b) AP + bulk NiO; (c)
pure AP.
Fig. 3. FTIR spectra of: (a) NiO nanoparticles; (b) bulk NiO.
only one weight loss step, corresponding to the exothermic
peaks of the DTA curves. The onsets of thermal decomposi-
tion of the three samples are all at about 300 ◦C, while the
end temperatures are about 450, 400 and 370 ◦C, respectively.
The thermal decomposition rate of AP in presence of NiO
nanoparticles is the fastest, AP in presence of bulk NiO is
slower, pure AP is the slowest.
Adding 2% of NiO nanoparticles to AP decreases the tem-
perature of thermal decomposition by 93 ◦C and increases
the heat of decomposition from 590 J g−1 (sublimation) to
1490 J g−1 (redox decomposition of AP).
The endothermic peak at 243 ◦C in Fig. 4 is due to a crystallo-
graphic transition [21]. The NiO additives have no effects on
the crystallographic transition temperature. The exothermic
peak at 347 ◦C in Fig. 4c is attributed to the partial decom-
position of AP and formation of some intermediate NH3
and HCIO4 by dissociation and sublimation [14,22,23]. The
exothermic peak at about 450 ◦C is caused by the complete
decomposition to volatile products. The heat of decomposi-
tion of pure AP is 590 J g−1. Noticeable changes can be seen
in Fig. 4b. The two exothermic peaks come closer and the
temperatures are lower. The heat of decomposition in pres-
ence of bulk NiO is increased to 932 J g−1
.
From Fig. 4a, with NiO nanoparticles added, one sharp
Acknowledgements
exothermic peak occurs at 357 ◦C with a heat of decomposi-
tion of 1490 J g−1
.
The authors are grateful for the financial support of
the National Natural Science Foundation of China (no.:
50372028) and National Defense Foundation of China (no.:
k1704061011).
The TG curves for pure AP, AP in presence of bulk NiO
and AP in presence of NiO nanoparticles are shown in Fig. 5.
Fig. 5c and b exhibit two weight loss steps, Fig. 5a exhibits
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