Navaratnasamy Karthikeyan
, Sri Jayewardenepura Kotte

Atomic, Molecular and Optical Physics, Experimental Physics, Materials Science

B.Sc. Physics, M.Sc. Physics,, M.Phil. Physics
11.35

Publications

  • N. Karthikeyan · V. Narayanan · A. Stephen
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    ABSTRACT: TiO2, SnO2 semiconductor nanomaterials and TiO2/SnO2 semiconductor nanocomposites with the weight percentages of 97:3, 95:5 and 90:10 were prepared. These as prepared materials were annealed at the optimized temperature of 450 0C for 2 hours. The crystalline structures of the prepared nanomaterials were confirmed by XRD and the surface morphology of the samples was studied by FESEM and TEM. The average crystallite sizes of the spherically shaped particles were found to be in the range from 4 nm to 11 nm. The elemental compositions of the catalysts were confirmed by EDX. The optical properties of the powder samples were analyzed with UV-VIS spectroscopy and their band gaps were estimated. Degradation abilities of the synthesized nanophotocatalysts on methylene blue and textile effluent collected from textile industries in Tiruppur, India were tested. The TiO2/SnO2(95:5) nanocomposite showed the best degradation efficiency.
    No preview · Article · Dec 2015 · International Journal of ChemTech Research
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    Navaratnasamy Karthikeyan · V. Narayanan · A. Stephen
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    ABSTRACT: Nano-Titania was synthesized by sol-gel method and the as prepared sample was annealed at various temperatures. Crystallinity, phase formations and structures of the annealed samples were examined by powder x-ray diffraction studies. The results revealed formation of pure anatase phase for annealing temperatures up to 600 0C and pure rutile phase at 900 0C. High resolution scanning electron microscope (HR-SEM) images showed granular morphology due to agglomeration of tiny spherically shaped particles. Energy dispersive x-ray (EDX) spectrometer analysis confirmed the expected elemental composition without any impurities. UV-Vis spectra revealed sharp absorption edges for all the samples in the UV region. Estimated optical bandgap showed shifts with the increasing annealing temperatures. The prepared photocatalysts were used for photocatalytic degradation of methylene blue dye to identify the best photocatalyst and then the best catalyst was employed for photocatalytic degradation of textile dye effluent under ultraviolet light irradiation. Among the prepared samples, Titania annealed at 450 0C produce the maximum decolouration during the testing time.
    Full-text · Article · Aug 2014
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    N. Karthikeyan · L. Prettencia · V. Narayanan · A. Stephen
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    ABSTRACT: Coupled ZnO/Ag/CuO nanophotocatalyst was prepared by thermal decomposition method. Also ZnO, Ag, CuO were separately synthesized by the same method under similar conditions, for comparative studies. The synthesized ZnO/Ag/CuO was annealed at various temperatures. The structure and the crystallinity of all the samples were confirmed by powder X-ray diffraction. The crystallite sizes were found to be in the range from 9 nm to 49 nm for different samples. The surface morphology and elemental composition were analyzed with FE-SEM and EDX Spectrometer. Optical properties of the samples were investigated with UV-Vis DRS spectrometer and the band gaps of the samples were estimated. Then the coupled nanophotocatalysts, treated at different temperatures, were employed to degrade the methylene blue dye under UV irradiation and the degradation efficiencies were studied. The nanophotocatalyst annealed at 400 0C exhibited the highest photocatalytic degradation efficiency.
    Full-text · Article · Jan 2014
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    ABSTRACT: Degradation of model organic dye and industry effluent was studied using different weight percentages of Ag into ZnO as a catalyst. In this study, the catalysts were prepared by thermal decomposition method, which was employed for the first time in the preparation of ZnO/Ag nanocomposite catalysts. The physical and chemical properties of the prepared samples were studied using various techniques. The specific surface area, which plays an important role in the photocatalytic degradation, was studied using BET analysis and 10wt.% Ag into ZnO showed the best degrading efficiency. The optical absorption (UV-vis) and emission (PL) properties of the samples were studied and results suggest better photocatalytic properties for 10wt.% Ag sample compared to other samples.
    Full-text · Article · May 2013
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    Full-text · Article · Jan 2013 · Materials Science and Engineering C
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    Navaratnasamy Karthikeyan · V. Narayanan · A. Stephen
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    ABSTRACT: Researches focusing on purification of the polluted water gain more and more importance as increasing contamination of ground water from industrial waste streams, especially textile dyes, plays a major role in polluting and causes a serious health and environmental problems. This study has focused on effect of annealing temperature on nanostructured TiO2/CuO binary photocatalysts in their efficiencies in degrading an azo dye. The CuO acts as sink for photo-generated electrons, prevents recombination and thus enhances the redox reactions which effectively enhance the decolouration of the water contaminated with azo dyes. Pure TiO2 and CuO nanomaterials, as well as TiO2 / CuO binary nanomaterials at the optimised weight percentage, were prepared. The samples were annealed at 300 0C, 450 0C, 600 0C, and 750 0C for 2 hrs and characterized by X-ray diffraction spectroscopy, field emission scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of the pure as well as TiO2 / CuO nanomaterials were evaluated using the photodegradation of Methylene Blue, an azo dye, under the irradiation of ultra violet light. It was found that the activity of TiO2 / CuO catalysts were higher than that of pure TiO2 or CuO. The ability of TiO2 / CuO nanomaterials in the degradation of Methylene Blue was found to change with the annealing temperature. The detailed results will be discussed in the manuscript.
    Full-text · Conference Paper · Dec 2012
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    ABSTRACT: Nanorods of ZnO/CeO2 were synthesized by thermal decomposition method. The decomposition temperature and formation of composite material were confirmed by the thermogravimetric analysis (TGA) before the synthesis process. The prepared samples were characterized by different techniques. The structural and morphological properties of ZnO/CeO2 nanorods were confirmed by X-ray diffraction (XRD) and high resolution scanning electron microscopy (HR-SEM). The chemical composition and specific surface area analysis were done by energy dispersive X-ray spectroscopy (EDX) and Brunauer–Emmett–Teller (BET) method. Further the catalyst was used for photocatalytic degradation of organic dye under visible light irradiation.
    Full-text · Article · Oct 2012 · Advanced Materials Research
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    ABSTRACT: In this study, cadmium oxide was prepared by thermal decomposition from their respective acetate without the use of any additive. This method is simple, fast and cost effective compared to other methods. Thermo gravimetric analysis of cadmium acetate was carried out before the actual synthesis process, to determine the dehydration, acetate decomposition and oxide formation temperatures. The structure and crystalline size of the prepared samples were confirmed by X-ray diffraction analysis. The XRD results indicate the formation of single crystalline CdO having a cubic structure. The HR-SEM images indicate the formation of pyramid shaped nano cadmium oxide. The bandgap value of pure CdO was examined by UV-Vis spectrometer. Further the sample was used for degradation of various dyes under UV light condition.
    No preview · Chapter · Jan 2012
  • Navaratnasamy Karthikeyan · R. Saravanan · A. Stephen
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    ABSTRACT: TiO2 and ZnO nanomaterials were prepared by Sol-gel method and annealed at 450 oC for 30 min. The XRD studies indicate tetragonal structure for TiO2 and hexagonal structure for ZnO. The morphological studies show spherical and rod shapes for TiO2 and ZnO respectively. The UV-Vis spectra demonstrated excellent absorption properties for the samples and they were used as catalysts for the photocatalytic degradation of methylene blue (MB) under UV light irradiation. The degradation of MB was studied and the degradation efficiencies of the prepared were compared.
    No preview · Chapter · Jan 2012
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    R. Saravanan · N. Karthikeyan · S. Govindan · V. Narayanan · A. Stephen

    Full-text · Article · Jan 2012 · Advanced Materials Research
  • Navaratnasamy Karthikeyan · R. Saravanan · A. Stephen
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    ABSTRACT: The removal of azo dyes from industrial effluents is one of the challenging environmental issues to be solved today. Photocatalytic degradation of azo dyes with semiconducting materials as catalysts attracted new researches owing to many advantages over other methods. The photocatalytic degradation of methylene blue, a commonly used azo dye in the industries such as textile, cosmetic and leather, was studied in aqueous medium containing titanium dioxide and zinc oxide as catalysts. The titanium dioxide and zinc oxide nanomaterials were prepared by Sol-gel method and the as prepared samples were annealed at 450 oC for half-an-hour. The structure and phases of the prepared samples were confirmed by powder X-ray diffraction (XRD) analysis. XRD results indicate single crystalline tetragonal structure for TiO2 and hexagonal structure for ZnO. The surface morphology (HR-SEM) and elemental analysis (EDX) shows spherical shape for TiO2 and rod shape for ZnO, both without any impurities. Absorption properties of TiO2 and ZnO nanoparticles were studied with UV-Vis spectrum. The UV-Vis spectrum demonstrated excellent absorption properties of TiO2 and ZnO nanoparticles. The prepared samples were used for the photocatalytic degradation of methylene blue under UV light irradiation. The comparative efficiencies of titanium dioxide and zinc oxide as catalysts in the photocatalytic degradation of methylene blue will be discussed in detail.
    No preview · Conference Paper · Dec 2011

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