Structural, Optical and Microscopy Analysis of ZnO-CuO Nanocomposite Thin Films K.Kavitha 1 , T.Ranjeth Kumar Reddy 2 , T. SubbaRao 3 , R.Padmasuvarna 1 , V.S.Vani 4 1 Department of Physics, Jawaharlal Nehru Technological University, Anantapur- 515002,,India 2 Presidency University, Bangalore-560064,India 3 Sri Krishnadevaraya University, Anantapur-515002, India 4 Holy Mary Institute of Technology & Science, Hyderabad-501301, India [email protected][email protected][email protected][email protected][email protected]Research Scholar,Department Of Physics,JNTUA, Anantapur- 515002.. 161 ISSN NO: 1301-2746 http://adalyajournal.com/ ADALYA JOURNAL Volume 8, Issue 12, December 2019
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Structural, Optical and Microscopy Analysis of ZnO-CuO
Nanocomposite Thin Films
K.Kavitha1, T.Ranjeth Kumar Reddy
2, T. SubbaRao
3, R.Padmasuvarna
1, V.S.Vani
4
1Department of Physics, Jawaharlal Nehru Technological University, Anantapur-
515002,,India
2Presidency University, Bangalore-560064,India
3Sri Krishnadevaraya University, Anantapur-515002, India
4Holy Mary Institute of Technology & Science, Hyderabad-501301, India
(CH COOH)(98%),NaOH (1M ) were used without further purification. All the chemicals are of FINAR grade. The
molecular weights of these chemicals are 219.498 gm-mol-1
, 199.65gm-mol-1
, 60.052 gm-mol-1
and 39.9 gm-mol-1
respectively.
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2.2 Synthesis of ZnO-CuO nanocomposite films
The synthesis of ZnO-CuO nanocomposites [9] were synthesized using simple chemical route i.e. dip coating. CuO-
ZnO (0.025M,0.05M and 0.075 M) nanocomposites have been prepared. All the chemicals used for synthesis are of
FINAR grade. Suitable molar ratios i.e. by using molarity calculation, the suitable amount of Zinc acetate [Zn
(CH COO)2.2H2O] and cupric acetate were dissolved in distilled water to acquire the above mentioned Molarity .
Acetic acid (CH COOH), having better solvent properties was added as a surfactant to these solutions. After
complete dissolution of precursors, NaOH (1M sol) was added drop-wise to adjust the pH value at 11. This is to
control the particle size and morphology of the material prepared. After adjusting the pH value, the solutions were
stirred for 2 hours at 100 ℃ to complete the reactions. The glass substrates were cleaned in an ultrasonic bath in
acetone, ethanol and distilled water respectively. The layers were deposited by immersing these substrates in the
solution and annealed at 500℃ for 2 hours in order to enhance the crystalline quality of the synthesized samples.
The porosity of the ZnO/CuO nanocomposite at 500 °C annealing temperature was 3.764% and at 600 °C it was
4.258 % (The theoretical density of ZnO/CuO composite is 4.7476 g/cc). This showed that when the annealing
temperature increased the porosity of the nanocomposite was also increased because of the agglomeration when
temperature increases agglomerations are found. It is noticed that, the porosity increased at 600℃, agglomeration
was observed. More the agglomeration, lesser will be the surface area [2]. Hence in the present work, the samples
for annealed at 500℃.
2.3 Methods of characterization
2.3.1. X-ray powder diffraction
The samples are obtained by keeping the dip coated substrates at annealing temperature 500°C. The
resultant samples are undergone XRD analysis. The structural characterization is performed by using X-ray
diffractometer of type Bruker Advance-D8 with CuKα 1.54 A°. The primary and secondary variable detectors involved
are Cu tube and Th scintillation.
2.3.2. UV-Visible Spectroscopy:
The absorption measurements of the material in liquid phase were obtained in order to observe the inclusion effect
of the nanocomposite powder. The double beam UV Visible spectrometer 2202 in scan mode of operation was used
for the collection of data. The gel samples were diluted in equal amount with ethanol as it was a solvent used in
synthesis.
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2.3.3. FTIR:
FTIR spectra of the samples were obtained using Thermo Nicolet Nexus 670 spectrometer of resolution 4/cm with a
detector DTGS KB and KBr beam splitter. KBr is used for sample preparation.
2.3.4: SEM-EDX:
The thin films are submitted to SEM of Zeiss EVO model to obtain the morphology and composition of the
samples. The SEM images of the thin film surfaces are obtained at 50 KX magnification by using SEM. The
microscope is operated in secondary electron detection at an accelerating voltage 10KV. The X- rays in the SEM
can be used to identify the elemental composition of the sample by Energy dispersive X-ray(EDX).
3. Results and Discussions
The size of the synthesized samples was determined by XRD pattern for ZnO-CuO nanocomposite thin films of
different molarities are shown in Fig. 1. The XRD peaks were well distinct and matching with JCPDS card numbers
36-1451 and 89-5899 for ZnO (hexagonal) and CuO (monoclinic) respectively [11]. The sharp peaks represent that
the obtained from nanocomposite thin film is having high crystallinity in nature. The data concludes that the obtained
the ZnO-CuO nanocomposite has been formed. The d-spacing values of ZnO-CuO nanocomposite thin films from
JCPDS card numbers are almost equal to d-spacing values measured from Bragg’s law. The result of XRD analysis
showed that ZnO diffraction pattern appears in the peak 2θ of 32.3°, 33.3° and 30.2°. Their interplanar spacing (d) at
these angles were determined by using miller indices (1 0 0), (0 0 2) and (1 0 1). These values are 2.810 Å, 2.667 Å,
and 2.476 Å respectively. Similarly, CuO diffraction pattern in the peak 2θ of 34.3° and 35.4°, 36.3° and 39.2° for
respectively as shown in the table.1.
Sample ZnO intensity at 2θ = 74⁰ Cuo intensity at 2θ =39⁰
0.025 M % 110 104
0.05 M % 68 334
0.075 M % 60 339
Table1: Intensity of CuO and ZnO in CuoO-ZnO
The d-values at indices (1 1 1), (1 0 1) and (1 1 1) are 2.518 Å, 2,486 Å, and 2.349 Å, respectively. The average
crystallite size was determined using Debye-Scherer’s formula, ⁄ Where K-Debye-Scherer’s constant, λ-
Wavelength of the radiation (CuKα1=0.154 nm), β-Full Width Half Maximum (FWHM) and θ-Bragg’s angle. As all the
samples were
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synthesized under same annealing temperature, there was no breaking of internal bond. The average crystallite size
was measured as ~22 nm to ~28 nm for different annealing temperatures. It can be concluded that that the particle
size was obtained as 34 nm from SEM. Hence the particle size was more than the average crystallite size [12,
23].This data is in good agreement with JCPDS 36-1451 and JCPS 05-0661[13].
The absorption spectra of ZnO-CuO nanocomposite thin films for different molarities are shown in Fig.2. At 500℃
annealing temperature, the absorbance varies with respect to wavelength with bandwidth 2 nm. The UV–Visible
spectra of the films were recorded from 200 nm to 1000 nm wavelength at room temperature [14]. After 330nm, the
absorbance decreases s shown in fig.2. In the formula Eg= 1240/λc where ‘λc’ is the cut-off wavelength for maximum
absorbance. Basing on Using this formula, the optical band gap was determined. The values of optical band gap are
3.5 eV, 3.3 eV and 3.1 eV for the ZnO-CuO nanocomposite thin films of different molarities i.e.0.025M, 0.05M and
0.075M respectively. It is clear that if the molarity is more then the thickness is more. As thickness increases,
resistance decreases which in turn band gap decreases. Also these samples are most suitable in gas sensors
because of low molarities [2].That means the sensitivity can be better. It is observed that because of low molarities
the variation of absorbance with wavelength is less in all the cases i.e. for 0.025M, 0.05 M and 0.075 M. Fig. 3 (a),
(b) and (c) shows the FTIR of ZnO-CuO nanocomposite thin films of different molarities 0.025M, 0.05 M and 0.075 M
respectively. FTIR spectra revealed that the presence of functional frequencies of ZnO and CuO were observed at
443 and 616 cm-1
[13, 19, 22, 26] for nanocomposites powder. The strong peaks around 1400cm-1
and 3400cm-1
represents that the hydroxyl groups and the stretching band of water molecules on the surface of nanocomposite
thin films. The CuO stretching band was obtained around 600 cm-1
. The peaks between 1000 to 1600 cm-1
represents the presence of C-H vibration of stretching band. ZnO stretching band was observed between 700 and
1300cm-1
. The range between 1000 and 2100 cm-1
indicates the weak vibration of absorbed CO2. The C=O and C-H
groups appeared because the synthesis used the precursor of Zn (CH3COO)2.2H2O that was not perfectly
decomposed to ZnO. The morphology, topography and composition of ZnO-CuO nanocomposite thin films were
studied using SEM and the results are depicted in Fig.4 (a), (b) and (c). The different shapes of nanoparticles were
observed from the images and the measured sizes of these shapes were coinciding with the size of nanoparticles
measured from XRD. The different sizes and shapes causes may be which are agglomerated due to growth in high
density of atoms [14]. The elemental composition of the prepared ZnO-CuO nanocomposite thin films shown in Fig.5
(a), (b) and (c) , which is investigated by using Energy Dispersive X-ray Spectroscopy (EDX). This observed
spectrum shows the presence of many well-defined peaks which are related with Zn, Cu and O only. Also, it is
observed that no other peaks related with impurities are present in the EDX spectrum, which confirmed the formation
and purity of ZnO-CuO nanocomposite [15-17]. Recently nanocomposite transducers have been arrived as a
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substitute for piezoelectric ceramics [18]. The degree of crystallinity can be increased by the incorporation of Nano
platelets [20]. The samples can be synthesized by several methods [21-25]. The nanocomposites prepared by these
methods have wide range of applications such as nano electronic device applications, gas sensors and antibacterial
activity etc.[28-34].
4. Conclusions
Low-cost ZnO-CuO nanocomposite thin films were synthesized by dip coating technique for different
molarities at constant 500 ℃ annealing temperature. The high crystalline nature of nanocomposite material and
average crystallite size were measured by X-ray diffractometer. The peaks confirmed that the obtained
nanocomposite thin films were ZnO as Hexagonal and CuO as Monoclinic. The energy band gap was found 3.5 eV,
3.3 eV and 3.1 eV for the ZnO-CuO nanocomposite thin films of different molarities using UV-visible spectrum. The
random shape and size was identified in SEM and given good support to the results of XRD. The result of EDX
confirms that, the presence of elements in nanocomposites was synthesized perfectly using Zinc acetate and cupric
acetate.
5. Future Scope:
ZnO-CuO nanocomposite is used for enhancing the photovoltaic performance of Dye sensitized solar cell. These characteristics are suitable for third generation photovoltaic technology which is to be studied in future work.
Conflict of interest:
The authors declare that they have no competing interests.
Acknowledgement:
Not Applicable
Funding:
Not applicable
Author’s contribution:
Author 1: Corresponding Author carried out the selection of nanocomposite and experimentation, acquisition of
data, characterization, and finding the applications.
Author 2: Author 2 participated in selection of journal, co-operated in overall development of the content.
Author 3: Author 3 participated in general supervision and approving of the research.
Author 4: Author 4 participated in general supervision and guidance.
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Author 5: Author 3 participated in the sequence alignment, performed the statistical analysis and helped to draft
the manuscript.
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[12]. S. Hussain, C. Cao, G. Nabi, W.S. Khan, M. Tahir, M. Tanveer, and I. Aslam 2017, “Optical and electrical characterization of ZnO/CuO heterojunction solar cells”, Optik-International Journal for Light and Electron Optics, vol.130, pp.372-377,.