The aims of this work are synthesis of ZnO nanopowders and producing nanocomposites by mixing with carbon nanotubes. ZnO nanopowders have been synthesized by chemical precipitation route. Dierent amount of collected nanosized Zn-based precipitates and chemically oxidized carbon nanotubes powder have been mix together and annealed at 400 • C. Characterization of produced nanopowders and nanocomposites have been carried out by X-ray diractometer and scanning electron microscope

D Gültekin

H Akbulut

M Alaf

CiteSeerX

Vol. 123 (2013) ACTA PHYSICA POLONICA A No. 2
Proceedings of the 2nd International Congress APMAS2012, April 2629, 2012, Antalya, Turkey
Synthesis and Characterization of ZnO Nanopowders
and ZnO-CNT Nanocomposites
Prepared by Chemical Precipitation Route
D. Gültekin∗, M. Alaf and H. Akbulut
Engineering Faculty, Metallurgical & Materials Engineering Department, Sakarya University
Esentepe Campus, 54187, Sakarya, Turkey
The aims of this work are synthesis of ZnO nanopowders and producing nanocomposites by mixing with carbon
nanotubes. ZnO nanopowders have been synthesized by chemical precipitation route. Dierent amount of collected
nanosized Zn-based precipitates and chemically oxidized carbon nanotubes powder have been mix together and
annealed at 400 ◦C. Characterization of produced nanopowders and nanocomposites have been carried out by
X-ray diractometer and scanning electron microscope.
DOI: 10.12693/APhysPolA.123.274
PACS: 61.46.Df, 81.07.Wx, 81.05.Dz, 61.48.De, 81.20.Fw
1. Introduction
Zinc oxide (ZnO) is an important material and has
received considerable attention due to its applications
in electrical, optical, mechanical, and scientic research.
ZnO is a wide band gap (3.37 eV) semiconductor and
has a large binding energy (60 meV) [1, 2], low resistivity
and high transparency in the visible range and high light
trapping characteristics [3]. The synthesis of nanopar-
ticles has become a highly developed eld owing to the
scientic and technological interest due to the structural
peculiarities and unusual physical and chemical proper-
ties they may lead to [4]. In recent years, it has been
found that ZnO can be synthesized by various routes
such as electron beam evaporation technique [5], chem-
ical spray pyrolysis technique [1], RF thermal plasma
evaporation [6], solgel method [3, 7], and precipitation
[1, 7] methods. Among these methods, precipitation has
many advantages over the other methods, for example,
it is unsophisticated and a low cost method. Moreover,
the morphology of ZnO powders can be controlled eas-
ily by using an appropriate surfactant or capping agent
such as polyethylene glycol, monoethanolamine (MEA),
diethanolamine or triethanolamine [7].
Over the past few years, great eorts have been made
toward the syntheses of nanocomposites of inorganic ma-
terials and carbon nanotubes (CNT) [8] with the aim
of exploiting the unique properties of CNTs (such as
a high theoretical electrical conductivity, high aspect
ratio, remarkable thermal conductivity, and good me-
chanical properties) [9]. In this work, ZnO nano pow-
ders and ZnO/multi-walled CNT (ZnO/MWCNT) nano-
-composites were synthesized and characterized.
∗corresponding author
2. Experimental
Figure 1 represents the process ow chart used for syn-
thesis of nanostructured ZnO powders by homogeneous
precipitation and producing of ZnO/MWCNT nanocom-
posites. Zinc acetate dihydrate (Zn(CH3COO)2·2H2O)
(Merck) was used as a precursor whereas distilled water
was used as solvents. Monoethanolamine (MEA) (Merck)
was used for adjusting of sol pH. MEA was added to ho-
mogeneous and transparent solution until white precipi-
tates are obtained. The pH value was recorded as 10. The
addition of MEA changes the alkaline nature of the pre-
pared sols that give ZnO lms with improved crystalline
quality [10]. After the precipitation, collected nanosized
powders were dried at 100 ◦C.
Fig. 1. The process ow chart used for synthesis of
nanostructured ZnO and ZnO/MWCNT nanocompos-
ite.
MWCNTs of over 10 ©m in length with outer diame-
ters of 50 nm were purchased from Arry Nano. In order
to eliminate ofamorphous carbon and remove impurities,
MWCNTs were annealed to 350 ◦C and then treated with
hydrochloric acid for one hour. Chemical oxidation of
CNTs was carried out with a mixture of sulphuric acid
and nitric acid in ratio 3:1 for 3 h. In order to enhance
the eciency, it is necessary to attach other substances
(274)
Synthesis and Characterization of ZnO Nanopowders . . . 275
to the surface of MWCNTs. Therefore, the surface mod-
ication of MWCNTs has been a focus of many environ-
mental scientists [11].
An appropriate amount of ZnO nanopowders and func-
tionalized MWCNTs (ZnO/MWCNT ratios are 5:1 and
2:1, respectively) were rst dispersed into water by mag-
netic stirrer and ultrasonicated for 30 min to form a well
dispersed. Since the boiling point of MEA and the ther-
mal decomposition temperature of zinc acetate dihydrate
are 170 and 240 ◦C, respectively, a heat treatment tem-
perature of 300 ◦C is sucient for the complete evapora-
tion of organics and to initiate the process of formation
and crystallization of the ZnO lm [10] fabricated coat-
ings annealed at 400 ◦C.
3. Results and discussions
The formation of ZnO particles from the hydroly-
sis of Zn2+ ions in aqueous media is known to be a
complex process. Many polyvalent cationic species can
be formed between Zn2+ ions with OH− ions and are
strongly dependent upon the pH of the solution. How-
ever, the precipitation of ZnO particles has been usu-
ally described through a growth unit that might be ei-
ther Zn(OH)2 or Zn(OH)
2−
4 ions depending on the pH,
temperature, and synthetic methods. The growth of
ZnO from Zn(OH)2 has been usually suggested to occur
through the dissolution-reprecipitation mechanism [12].
ZnO will be formed through the chemical reaction [10]:
Zn(OH)2 → ZnO + H2O.
Figure 2 presents the X-ray diraction (XRD) patterns
of synthesized powder and nanocomposites. The peak
positions in each product agree well with the reections of
bulk ZnO and ZnO/CNT composites with all peaks cor-
responding well to standard crystallographic data (ZnO:
JCPDS 01-076-0704, C: JCPDS No. 00-026-1080). As
could be seen from the XRD patterns, all products have
polycrystalline nature and peaks belonging to the (100),
(002), (101) (102), (110), (103), (112) and (201) reec-
tions were seen in ZnO powders, also (002) reection
for C. No other peak related to impurities was detected
in the spectrum, which further conrms that the syn-
thesized products are of high purity. The ZnO powders
show a highly oriented (101), (100) and (002) peaks, re-
spectively. Although it was obtained that there has been
slight changing in orientation and peak intensities with
an increasing amount of CNT.
TABLE
XRD diraction peaks information 2Θ of ZnO and ZnO/
CNT nanocomposites.
(hkl) ZnO ZnO/CNT 5:1) ZnO/CNT 2:1)
(100) 31.680 31.680 31.680
(002) 34.320 34.339 34.380
(101) 36.160 36.158 36.141
As could be seen in Table, the XRD peaks shifting
of ZnO and ZnO/MWCNT nanocomposites were inves-
tigated and reveal the eect of the amount of CNT. It
Fig. 2. The XRD diraction patterns of ZnO and
ZnO/MWCNT products.
was observed that there have been slight increases/de-
creases between XRD peaks angle belonging to ZnO and
ZnO/MWCNT nanocomposites. While a peak was ob-
served at 34.320◦ from the XRD 2θ scan data of the pure
ZnO nanopowders corresponding to ZnO (002), ZnO/
MWCNT nanocomposites resulted in shifting XRD peaks
to a higher angle. Furthermore, ZnO/MWCNT (5:1)
and ZnO/MWCNT (2:1) nanocomposites peak shifts to
36.158◦, and 36.141◦, respectively. The peak shift in the
XRD curves originates from dierence between ZnO and
ZnO/MWCNT lattice constants. These peaks shifts may
indicate a lattice strain between ZnO and CNTs.
Fig. 3. SEM micrographs of (a) ZnO, (b) ZnO/CNT
5:1, (c) ZnO/CNT 2:1.
Grain morphologies of ZnO powders can be observed
from SEM images represented in Fig. 3. The grain sizes
of the ZnO powders were calculated by using Scher-
rer's formula and the crystallite size is 26 nm. In the
literature, ZnO nanostructures having 9250 nm have
been reported [13]. The nanostructure has both approx-
imately 0.11 µm sized agglomerated nanoparticles and
276 D. Gültekin, M. Alaf, H. Akbulut
prism-like nanoowers. It was observed that nanocom-
posite structures have well-dispersed carbon nanotubes
network.
4. Conclusions
Polycrystalline and nanostructured ZnO powders were
successfully produced by homogeneous precipitation
route, then ZnO/MWCNT nanocomposites were pre-
pared by physically mixing with nanopowders. The ef-
fects of amount of CNT on the properties of powders
have been presented. The XRD patterns of all prod-
ucts were of polycrystalline nature. Experimental results
showed that although the crystal orientations and parti-
cle sizes of the prepared ZnO particles were not aected
with amount of CNT, slight increases/decreases in XRD
peaks angle were observed. The intensity of the (101)
orientation is predominant for ZnO and ZnO/MWCNT
products. ZnO nanoparticles and CNTs combined to-
gether and results showed that ZnO and nanotubes kept
their structure and formed a nanocomposite. ZnO and
nanotubes have not reacted with each other.
Acknowledgments
The authors would like to acknowledge the nancal
support of Sakarya University, Coordination of Scientic
Research Project (BAPK) under the contract number
2009-50-02-023.
References
[1] B.B. Rao, Mater. Chem. Phys. 64, 62 (2000).
[2] S. Ilican, Y. Caglar, M. Caglar, F. Yakuphanoglu,
Appl. Surf. Sci. 255, 2353 (2008).
[3] Y. Caglar, S. Ilican, M. Caglar, F. Yakuphanoglu,
Spectrochim. Acta A 67, 1113 (2007).
[4] C.A. Ibarguen, A. Mosquera, R. Parra, M.S. Castro,
J.E. Rodriguez-Paez, Mater. Chem. Phys. 101, 433
(2007).
[5] D.R. Sahu, S.Y. Lin, J.L. Huang, Microelectr. J. 38,
245 (2007).
[6] J. Tsujinoa, N. Homma, T. Sugawara, I. Shimono,
Y. Abe, Thin Solid Films 407, 86 (2002).
[7] S. Suwanboon, P. Amornpitoksuk, N. Muensit, Ce-
ram. Int. 37, 2247 (2011).
[8] J. Yu, J. Fan, B. Cheng, J. Power Sources 196, 7891
(2011).
[9] L.S. Ying, M.A.M. Salleh, H.M. Yuso,
S.B.A. Rashid, J. Razak, J. Industr. Eng. Chem.
17, 367 (2011).
[10] P. Sagar, P.K. Shishodia, R.M. Mehra, Appl. Surf.
Sci. 253, 5419 (2007).
[11] T.A. Saleh, M.A. Gondal, Q.A. Drmosh, Z.H. Ya-
mani, A. Al-Yamani, Chem. Eng. J. 166, 407 (2011).
[12] N. Samaele, P. Amornpitoksuk, S. Suwanboon, Pow-
der Technol. 203, 243 (2010).
[13] Y.S. Kim, W.P. Tai, S.J. Shu, Thin Solid Films 491,
153 (2005).


Synthesis and Characterization of ZnO Nanopowders and ZnO-CNT Nanocomposites Prepared by Chemical Precipitation Route

http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=7A1843E1BB2368D7DC8379C1E11574F9?doi=10.1.1.1050.1197&rep=rep1&type=pdf

Synthesis and Characterization of ZnO Nanopowders and ZnO-CNT Nanocomposites Prepared by Chemical Precipitation Route

Abstract

Similar works

Full text

Available Versions

CiteSeerX