Journal of Nanomaterials & Molecular NanotechnologyISSN: 2324-8777

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Research Article, J Nanomater Mol Nanotechnol Vol: 6 Issue: 2

Synthesis and Characterization Studies of Pb:Zr:/O2 Nanorods for Optoelectronic Applications

Kaviyarasu K1,2*, Xolile Fuku1,2, Kotsedi L1,2, Manikandan E1,3, Kennedy J1,4 and Maaza M1,2
1UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria, South Africa
2Nanosciences African network (NANOAFNET), Materials Research Department (MSD), iThemba LABS-National Research Foundation (NRF), 1 Old Faure Road, 7129, P O Box 722, Somerset West, Western Cape Province, South Africa
3Central Research Laboratory, Sree Balaji Medical College & Hospital, Bharath University, Chrompet, Chennai 600044, Tamil Nadu, India
4National Isotope Centre, GNS Science, Lower Hutt, New Zealand
Corresponding author : Kaviyarasu K
UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria, South Africa
Tel:
+27630441709
E-mail: [email protected]
Received: June 21, 2016 Accepted: December 31, 2016 Published: January 07, 2017
Citation: Kaviyarasu K, Fuku X, Kotsedi L, Manikandan E, Kennedy J (2017) Synthesis and Characterization Studies of Pb:Zr:/O2 Nanorods for Optoelectronic Applications. J Nanomater Mol Nanotechnol 6:2. doi: 10.4172/2324-8777.1000211

Abstract

Synthesis and Characterization Studies of Pb:Zr:/O2 Nanorods for Optoelectronic Applications

In the present work, we have synthesized ZrO2 doped PbO2 nanocrystals were successfully prepared by hydrothermal method which is Zirconium nitrate hydrate (Zr(NO3)4.5H2O) and lead nitrate (Pb(NO3)2) were used as a precursor. In the experimental results show that the amount of Iodine (I) and the NaOH concentration plays a important roles in the formation of hexagonal defined amount of ethylene glycol at 900 °C within 21 hrs. In the physiochemical properties of Zr doped lead oxide nanorod were determined by using X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV-vis), Fourier Transform Infrared spectroscopy (FTIR) and Transmission electron microscope (TEM). In Zr doped Pb oxide nanorods were the highest photon activity under both UV and visible light irradiation.

Keywords: Electron microscopy; Semiconductors; Microstructure; Energy storage and conversion; Powder technology

Keywords

Electron microscopy; Semiconductors; Microstructure; Energy storage and conversion; Powder technology

Introduction

In semiconducting materials have been identified as materials with potential applications in wide ranged areas including biological labeling and diagnostics light-emitting diodes, electroluminescent devices, photovoltaic devices, lasers and single-electron transistors [1-3]. Recently many papers have been published relating to quantum confinement effects in semiconductor systems with reduced space dimensions which have attracted considerable interest owing to their low cost [4], good electrical conductivity [5], high oxygen over potential and chemical stability in acid media. A variety of electrochemical and industrial applications have been reported for lead dioxide such as lead acid batteries [6], electrochemical synthesis [7], ozone generation and oxidation of organic pollutants in wastewater treatment [8,9]. In order to further improve the electrochemical stability of lead dioxide electrodes incorporating some nanoparticles into lead dioxide matrix has been investigated and several literature reports are available on the preparation of composite electrode materials containing nanoparticles of different metal oxides including Co3O4, TiO2, La2O3 and RuO2 [10-12]. The electrode material is a crucial factor for optimizing electrochemical oxidation condition; more attention has been focused on the exploration of novel anode materials to improve the electrocatalytic properties [13]. Since, Lead dioxide nanoparticles have been used as anode material for organic pollutant degradation because of its good electrical conductivity for anodic oxidation and relatively low cost and also it has been widely investigated for application in wastewater treatment fields [14-16]. So, we prepared Zr:Pb electrodes comprising composite nanoparticles and the influence of Zr nanoparticles were investigated [17]. The physical and chemical properties of the nanocomposites were studied by High resolution Scanning electron microscopy (HRSEM) and cyclic voltammogram [18-20]. In this technologically important wastewater treatment process it is also mandatory to assemble semiconductor nanorods in an orderly form and simultaneously important to retain the physicochemical properties of each individual nanoparticles. Hence the development of producing materials with nanometer dimension using novel, simple and low cost route is of current interest. Furthermore, the potential mechanisms for the formation of Zr:Pb nanocrystallites were discussed.

Experimental

Chemicals
All the chemical reagents used in this experiment were of analytical grade (E-Merck, 99.99%) procured commercially and were used without further purification.
Typical synthetic process of lead oxide nanocrystals
A solution mixture containing 0.10 mol % of lead dioxide and 0.5 mol % of zinc oxide was taken in a beaker and the resulting mixture was stirred thoroughly using a magnetic stirrer. This precursor was added to 10 ml of 0.5 g concentration of H2SO4 solution, to get a white semi transparent solution. Then, the reaction solution was rapidly heated by immersing the beaker in oil bath kept at 190 °C for 12 hrs to ensure the completeness of reaction. Then the solution color became gradually thicker in color with the increase of reaction time till it changed into black completely, demonstrating the formation of Zr doped Pb composite nanomaterials. The resulted solution was cooled to room temperature naturally, and mixed with ethyl alcohol to precipitate Zr doped Pb nanoparticles in the form of nanorods. The precipitated black product was collected by centrifugation and thoroughly wasted with ethanol for further characterization.
Sample characterization
The X-ray powder diffraction (XRD) experiments were carried out on a RigaKu D/max-RB diffractometer with Ni-filtered graphite monochromatized Cukα radiation (λ=1.54056Å) under 40 kV, 30 mA and scanning between 10° and 80° (2θ). The Scanning Electron Microscopy (SEM) micrographs were taken using a Philips XL-30. The lattice structure of the nanocrystallites were detected by High resolution transmission electron microscopy (HRTEM) with a (JEM 1200, JOEL) microscope with an accelerating voltage of 100 kV.

Results and Discussion

XRD pattern for Zr2:Pb nanorods
The phase identification of Zr doped Pb nanocrystallites samples were recorded by powder X-ray diffraction technique employing Cu Kα radiations in the 2θ range 10°-80°. The XRD pattern of Zr doped Pb nanorods are shown in Figure 1. All the peaks can be assigned to either Zr phase or Pb. XRD pattern corresponds to Zr doped Pb composite only without no other new phases. The particle size of the prepared samples is evaluated by using Scherrer formula d=0.98λ/ßCosθ Where, d is average particle size, β is full width half maxima (FWHM), θ is Bragg’s angle and λ is the wavelength of CuKα radiations. It was observed that particle size decrease on increasing the calcination time and the particle size becomes less than 100 nm for the sample calcinated at 600°C for 7 hrs. To evaluate the bandgap of the synthesized nanocomposites UV-vis absorption spectrum was recorded in the wavelength range from 200-750 nm. The spectra of the nanoparticles calcinated for 7 hrs at 600°C are shown in the Figure 2. The study of UV-vis radiation absorption is an important tool for the evaluation of the changes in the produced semiconductor material by different treatments. The bandgap energy of the nanocomposites was calculated on the basis of maximum absorption band of Zr doped Pb nanoparticles according to the equation. Eg=1240/λ, Where, Eg is the band gap energy and λ is the lower cutoff wavelength in nanometer (nm) and the calculated band gap value of the calcinated composites comes out to be 3.4 eV. Since a blue shift is observed from the absorption spectra for the calcinated samples, it confirms the formation of nanocomposites.
Figure 1: XRD pattern for Zr:Pb nanorods.
Figure 2: FTIR image of Zr:Pb nanorods.
FTIR image of Zr:Pb nanorods
The Fourier Transform Infra-Red (FTIR) spectrum of the as obtained Zr doped Pb nanorods are shown in Figure 3. The FTIR spectrum of the Zr doped Pb nanorods were recorded with 4 cm-1 resolution and 2° mm/s scanning speed. The recorded FTIR spectra were compared with the standard spectra of functional groups and Figure 3 shows the FTIR spectrum in the wavelength range 400- 4000 cm-1. A broad band at 3433 cm-1 corresponds to stretching mode of OH group which is contributed by water contents. The peak around 2338 cm-1 is due to C=C bond. Band around 1369 cm-1 is due to C=O bond and band around 1666 cm-1 is due to deformation vibration of H2O molecule. Band around 1369 cm-1 may correspond to asymmetric stretching of C=O bonds band around 837 cm-1 may be due to single C-C bond stretching mode the band at 466 cm-1 may be corresponding to stretching vibration of M-O-M bond and band around 850 to 450 cm-1 is due to metal oxide. The FTIR peaks at 290 cm-1 and 366 cm-1 is the characteristics vibration of Zr-Pb-O.
Figure 3: SEM & TEM images of Zr:Pb nanorods.
SEM and TEM images of Zr:Pb nanorods
The morphology and microstructure were studied by SEM and HRTEM, and the results are depicted in Figure 3(a-f). As seen from the SEM images as shown in Figure 3(a-c), the product is comprised of micron-sized cubic-like structures constructed by rodlike nanofibers. The high magnification SEM image shown in Figure 3(b) which reveals that they are of smooth surfaces and rectangular cross section with a diameter of 10 μm and have a length up to several hundred nanometers. The rod-like shape of the nanocomposites can be confirmed unambiguously in the low-magnification SEM image displayed in Figure 3(a). To study the detailed lattice structure, theSEM image and its EDS image are carried out. Uniform and regular lattice fringes can be seen clearly, which confirms that the nanorods are ideal single crystals without any other phases such as Zr nanocrystals. The interplanar distances of the two groups of crystallographic planes marked in the image have been measured to be 0.42 nm and 0.29 nm, respectively, matching well with the (110) and (101) planes of rutile Zr, and indicating that the growth direction is 211. Figure 3(d,f) shows HRTEM images of pure Zr doped Pb nanorods which confirm the growth of uniform and elongated particles that can easily reach lengths of 1 μm or more. The dimension of Zr doped Pb nanorods can grow to such long lengths because a growth time of 7 hrs was used and nanofibers with lengths of a few microns can be synthesized by reducing the growth time to less than1hr. Figure 3(e,f) shows a high-magnification view of the pure Zr doped Pb nanorods which appear straight and flexible with smooth surfaces; the diameters of these nanorods range mostly between 50 nm and 100 nm. These observations confirm the formation of one dimensional (1D) Zr:Pb nanorods.

Conclusion

Zr doped Pb nanoparticles have been successfully synthesized by solvothermal route. The structural, morphological and optical properties of Zr doped Pb nanorods are investigated using by the X-ray powder diffraction (XRD), Ultraviolet-visible infrared (UV-vis-NIR), Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) analysis.

Acknowledgments

The authors gratefully acknowledge research funding from UNESCOUNISA Africa Chair in Nanosciences/Nanotechnology Laboratories, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, Pretoria, South Africa, (Research Grant Fellowship of framework Post-Doctoral Fellowship program under contract number Research Fund: 139000). One of the authors (Dr. K. Kaviyarasu) is grateful for Dr. Prof. M. Maaza, Nanosciences African network (NANOAFNET), Materials Research Department (MRD), iThemba LABS-National Research Foundation (NRF), Somerset West, South Africa. Support Program and the Basic Science Research Program through the National Research Foundation of South Africa for his constant support, help and encouragement generously.

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