The effect of concentration ratio and type of functional group on synthesis of CNT–ZnO hybrid nanomaterial by an in situ sol–gel process
The effect of concentration ratio and type of functional group on synthesis of CNT-ZnO hybrid nanomaterial by an in situ sol- gel process
Sekineh Hosseini Largani 0
Mohammad Akbarzadeh Pasha 0
0 Research Laboratory of Carbon-based Nanostructures, Faculty of Basic Science, University of Mazandaran , Babolsar , Iran
In this research, MWCNT-ZnO hybrid nanomaterials were synthesized by a simple sol-gel process using Zn(CH3COO)2 2H2O and functionalized MWCNT with carboxyl(COOH) and hydroxyl(OH) groups. Three different mass ratios of MWCNT:ZnO = 3:1, 1:1 and 1:3 were examined. The prepared nanomaterials were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR). Successful growth of MWCNT-ZnO hybrids for both COOH and OH functional groups and all the three mass ratios were obtained. The ZnO nanoparticles attached on the surfaces of CNTs have rather spherical shapes and hexagonal crystal structure. By increasing the concentration of ZnO, the number and average size of ZnO nanoparticles decorated the body of CNTs in hybrid structures increase. By increasing the ZnO precursor, the distribution of ZnO nanoparticles that appeared on the surface of CNTs becomes more uniform. The SEM observation beside EDX analysis revealed that at the same concentration ratio the amount of ZnO loading on the surface of MWCNT-COOH is more than MWCNT-OH. Moreover, the average size of ZnO nanoparticles attached on the surface of COOH functionalized CNTs is relatively smaller than that of OH functionalized ones.
Carbon nanotubes; ZnO nanoparticles; CNT-; ZnO hybrid; Sol-gel; Concentration ratio; Functional group
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Because of their unique physical and chemical properties,
carbon nanotubes (CNTs) are considered to be excellent
candidates for many potential applications such as nanocomposite
materials, nanoelectronics, catalysis and sensors [1–10]. Due to
their great hardness and toughness, multiwall CNTs
(MWCNTs) keep their morphology and structure even at high
nanoparticle loadings [11]. It has been indicated that the CNTs’
properties can be dramatically influenced by the surface
modification with organic, inorganic and biological species [12–14].
Many metal oxides and sulfides such as TiO2, Cu2O, Al2O3,
Co3O4, MgO, FexOy, ZnS and CdS have been used to modify
the CNTs [12–15]. Zink oxide is a semiconductor material with
an energy gap of 3.37 eV and a large exciton binding energy
(60 meV) at room temperature [16–19]. ZnO has remarkable
physical and chemical properties including nontoxic nature,
low cost, high optical activity and stability, high sensitivity of
UV–Vis light and high thermal and mechanical stability at
room temperature [12, 13, 16, 17, 20, 21]. These properties
revealed that the ZnO is a useful material in electronics, optics,
photonics, room temperature UV lasers, light emitting diodes
and sensors [10–13, 20, 22]. Also it is applicable in
photocatalytic degradation of organic pollutants under UV–Vis light
[9, 20, 23].
MWCNT–ZnO hybrids have unique properties different
from alone CNT and ZnO [9, 12]. CNTs are good electron
acceptors and ZnO is a good electron donor under UV
illumination. MWCNTs act as photogenerated electron acceptors
to promote interfacial electron transfer process from the
attached ZnO to CNTs. Thus, the recombination of photo
induced electron and hole would be retarded. This process
enhances the photocatalytic activity of CNT–ZnO hybrid
nanostructures [11]. Chen et al. synthesized ZnO
nanoparticles decorated MWCNTs nanocomposite by a sol–gel method
and observed that by increasing the calcination temperature
from 450 to 700 C the sizes of ZnO nanoparticles increase
and the layer of coated ZnO becomes discontinuous [13].
Wang et al. conducted a report on covalent attachment of ZnO
nanostructures to MWCNTs through C-N bonds. Two
different morphologies of nanohybrids; flower-like ZnO on the
tips of MWCNTs and ZnO nanoparticles on the surface of
MWCNTs were obtained via adjusting the reaction time [12].
Yang et al. utilized an ex situ chemical preparation of CNT–
ZnO nanohybrids and observed that addition of a cationic
surfactant (cetyltrimethylammonium bromide; CTAB)
prevents the agglomeration of ZnO nanoparticles and results in
uniform distribution of ZnO nanoparticles decorated on
CNTs’ surfaces [10]. Our present work aims to grow the
valuable CNT–ZnO nanostructures by a simple sol–gel
method. Furthermore the effect of precursor concentration
ratio and type of CNTs’ functional group on synthesis of this
nanostructure was investigated. Although CNT–ZnO
nanohybrids were successfully synthesized by various
methods, further exploration is still motivated [10–13, 15 and
references there in]. The structure and morphology of CNT–ZnO
hybrids are very sensitive to experimental parameters
especially by sol–gel process [10–13, 15 and referenc (...truncated)