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Author: search.filters.author.Balavijayalakshmi JSubject: search.filters.subject.Graphene oxide

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    STRUCTURAL AND MORPHOLOGICAL ANALYSIS OF POLYMER FUNCTIONALIZED GRAPHENE OXIDE – METAL OXIDE NANOCOPOSITES
    (Sri Ramakrishna Engineering College, Coimbatore., 2018-07-18) Reeshma P; Balavijayalakshmi J
    Graphene is a two dimensional honeycomb arrangement of carbon atom that revolutionize our world in the field of technology. Graphene and its derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), are ideal platforms for constructing graphene-based nanostructures for various applications. A new type of graphene oxide /chitosan /MnO2 Nanocomposites are prepared. In this present work, graphene oxide is prepared from natural graphite flakes by modified hummers method, then graphene oxide /chitosan/MnO2 Nanocomposites is synthesised via. chemical co–precipitation method from the mixture of solution of GO, Chitosan and KMnO4. The structural and morphological properties of the prepared nanocomposites are investigated by X-Ray diffraction analysis and Field emission scanning electron microscopy (FE-SEM). The presence of functional groups in the synthesized nanocomposites are studied by Fourier transform infrared spectroscopy(FT-IR).Energy dispersive X-Ray Analysis (EDAX) is used to identify elemental composition of materials. The prepared nanocomposites may be employed for removal of heavy metal ions from waste water.
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    A STUDY ON STRUCTURAL, SPECTRAL AND MORPHOLOGICAL ANALYSIS OF POLYMER FUNCTIONALIZED GRAPHENE OXIDE – METAL OXIDE NANOCOMPOSITES FOR REMOVAL OF DYES FROM AQUEOUS SOLUTION
    (Centre for NanoScience and Technology, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Hyderabad, 2018-10-04) Reeshma P; Balavijayalakshmi J
    Graphene is a two dimensional honeycomb arrangement of carbon atom that revolutionize our world in the field of technology. Graphene and its derivatives such as graphene oxides (GO) and reduced graphene oxides (rGO) are ideal platforms for constructing graphene-based nanostructures for various applications. Chitosan(CS) is a natural bio polysaccharide and the most abundant polymer. It has attracted considerable research interest due to its tremendous applications in agriculture, biopesticides etc. Manganese oxides are attractive inorganic materials owing to their low cost, high chemical stability, high electro chemical activity and eco friendly nature, which have a wide range of applications in super capacitors, heavy metal ion removal, dye removing etc. In this present work, graphene oxide is prepared from natural graphite flakes by modified hummers method and then graphene oxide /chitosan/MnO2 nanocomposites is synthesised via. chemical reduction method from the mixture of solution of GO, Chitosan and KMnO4. The structural and morphological properties of the prepared nanocomposites are investigated by X-Ray diffraction analysis and Field emission scanning electron microscopy (FE-SEM). The presence of functional groups in the synthesized nanocomposites are studied by Fourier transform infrared spectroscopy(FT-IR).Energy dispersive X-Ray Analysis (EDAX) is used to identify elemental composition of materials. The prepared nanocomposites are used for dye removing application. The adsorption properties of graphene oxide /chitosan /MnO2 towards industrial dyes are investigated along with measured effect of adsorption by initial concentration, contact time and pH values. The resulting adsorption isotherm is analyzed systematically. These nanocomposites are found to be more efficient adsorbent for the removal of anionic industrial dyes.
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    IMPACT OF ENCAPSULATED METAL NANOPARTICLES ON POLYMER FUNCTIONALIZED GRAPHENE NANOCOMPOSITES FOR ITS SENSING APPLICATIONS
    (Centre for NanoScience and Technology, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Hyderabad, 2018-10-04) Balavijayalakshmi J; Ramalakshmi V
    The present work describes the synthesis of beta cyclodextrin functionalized silver nanoparticles encapsulated graphene oxide nanocomposite for the sensitive electrochemical detection of nitrophenol (NP) isomers. The functionalization and encapsulation of graphene oxide surface using beta cyclodextrin and silver nanoparticles are done by using chemical reduction of graphene oxide, beta cyclodextrin and silver nitrate chemical reagents. The physico-chemical properties of synthesized GO-CD-Ag nanocomposites are investigated using XRD, SEM, TEM and RAMAN analytical techniques [1]. The SEM and TEM morphological analysis confirms that the beta cyclodextrin molecules are effectively covered on the surface of graphene oxide nanosheets and also the silver nanoparticles are uniformly encapsulated on the surface of beta cyclodextrin functionalized graphene oxide nanosheets. The synthesized GO-CD-Ag nanocomposite modified GCE is employed for the sensitive detection of nitrophenol isomer such as para-nitrophenol (p-NP) and meta-nitrophenol (m-NP). The cyclic voltammetry studies show that the GO-CD-Ag nanocomposite modified GCE exhibits a good electrochemical behaviour for the reduction of p-NP and m-NP isomers in PBS solution [2]. The enhancement in the electrochemical behaviour of graphene oxide may be due to the host guest recognition properties of beta cyclodextrin and electronic properties of silver nanoparticles. The synthesized GO-CD-Ag nanocomposite modified electrochemical sensor exhibits the linear detection limits of 25 mm and 15 mm for p-NP and m-NP, respectively.
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    POLYMER FUNCTIONALIZED REDUCED GRAPHENE OXIDE BASED NICKEL NANOPARTICLES AS HIGHLY EFFICIENT DYE CATALYST FOR WATER REMEDIATION
    (International and Interuniversity Centre for Nanoscience and Nanotechnology (IIUCNN), Mahatma Gandhi University, Kottayam, Kerala, 2018-05-11) Ramalakshmi V; Balavijayalakshmi J
    The present work describes the synthesis and characterization of reduced graphene oxide based nickel nanoparticles containing beta cyclodextrin composite and its application for removal of textile dye from aqueous medium. For this purpose graphene oxide is produced by modified Hummer’s method, then after, GO-CD and GO-CD-Ni nanocomposites are synthesized via wet chemical method. The synthesized adsorbents (GO, GO-CD and GO-CD-Ni) are characterized using different characterization techniques such as FT-IR, XRD, FE-SEM. Also, the various parameters affecting dye removal like pH, contact time, amount of adsorbents and initial dye concentrations are investigated. The synthesized adsorbents exhibits excellent adsorption performance for the removal of textile dyes. The adsorption process is pH dependent and the adsorption capacity is increased with the increase in contact time and with that of adsorbent dosage.
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    A FACILE SYNTHESIS AND INVESTIGATION ON METAL OXIDE NANOPARTICLES EMBELLISHED GRAPHENE OXIDE NANOCOMPOSITES
    (Royal Book publishers / PSGR Krishnammal College for Women, Coimbatore, 2018-01-03) Ramalakshmi V; Balavijayalakshmi J; Roshini P
    Graphene is a flat monolayer of carbon atoms with sp2-hybridized two-dimensional carbon structure. Graphene’s fascinating high conductivity, superior electron mobility, extremely high specific surface area and easy functionalization make graphene a good substrate to yield graphene-based nanocomposites. Metal oxides nanomaterials have considerable attention due to their unique properties that can be used for designing advanced nanodevices. Thus, in the present study metal oxide nanoparticles embellished graphene oxide nanosheets (GNs) is synthesized and characterized. The graphene oxide nanosheets are produced by modified Hummer’s method. The metal oxide nanoparticles are loaded on the synthesized graphene oxide nanosheets via chemical reduction method. The metal oxide nanoparticles embellished graphene oxide nanosheets are characterized using Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction analysis and Field emission scanning electron microscopy (FE-SEM). The structural properties of the synthesized nanocomposites are characterized using X-Ray diffraction analysis and the result confirms that the synthesized nanocomposites are well crystalline. The morphology of synthesized nanocomposites is analyzed using field emission scanning electron microscopy analysis.
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    DECORATION AND FUNCTIONALIZATION OF GRAPHENE OXIDE NANOCOMPOSITES FOR SENSING APPLICATIONS
    (Royal Book publishers / PSGR Krishnammal College for Women, Coimbatore, 2018-01-03) Ramalakshmi V; Balavijayalakshmi J
    In the present work, β-cyclodextrin functionalized reduced graphene oxide-silver nanocomposites (GO-β-CD-Ag) are effectively synthesized using wet chemical method. The GO-β-CD nanocomposites are initially produced via hydrazine reduction. The various concentrations (0.002 M, 0.004 M, 0.006 M, 0.008 M and 0.01 M) of silver nanoparticles are decorated on the GO-β-CD surface by the reduction of silver nitrate with sodium borohydrate as a reducing agent. The produced GO-β-CD-Ag nanocomposites are well characterized using XRD, SEM and EDAX analysis. The XRD results firmly established that the β-CD molecules are satisfactorily coated on the rGO surface and also the Ag nanoparticles with an average size of 23 nm are evenly decorated on the GO-β-CD surface. The GO-β-CD-Ag nanocomposites modified glassy carbon electrode is captivated for the selective detection of o-Nitrophenol. Cyclic voltammetry test is employed to determine the presence of o-Nitrophenol compound. The result shows the oxidation and reduction potential for o-Nitrophenol at -0.25 V and -0.5 V respectively, indicating the successful determination of o-Nitrophenol by using the GO-CD-Ag nanocomposite modified electrode.
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    INVESTIGATION ON EMBELLISHMENT OF METAL NANOPARTICLES ON GRAPHENE NANOSHEETS AND ITS SENSING APPLICATIONS
    (Centre for Crystal Growth, VIT University, Vellore, 2017-10-09) Ramalakshmi V; Balavijayalakshmi J
    Nanotechnology promises breakthroughs in areas such as manufacturing nanoelectronics, medicine and healthcare, energy, biotechnology, information technology, and national security. The present work describes a general approach for the preparation of cyclodextrin functionalized (CD) graphene oxide nanosheets (GNs) for the embellishment of different concentrations of silver nanoparticles (Ag) on the surface of GNs. The graphene oxide nanosheets are synthesized by modified Hummer’s method. Firstly, CD/RGO nanosheets are synthesized through hydrazine reduction. The different concentrations of Ag nanoparticles are loaded on the CD/RGO nanosheets by the reduction of AgNO3 with NaBH4 as reducing agent. The synthesized CD/RGO/Ag nanocomposites are well characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and EDAX analysis. The results confirmed that the CD is effectively covered on the RGO surface and the Ag nanoparticles are uniformly decorated on the CD/RGO nanosheets [1]. The modified glassy carbon electrode was employed for the selective determination of phenolic compounds. Cyclic voltammetry measurements suggested that the CD/RGO/Ag nanocomposites exhibits an excellent electrochemical activity towards oxidation of phenolic compounds due to the host-guest recognition and enrichment capability of β-CD as well as the outstanding electronic properties of RGO and Ag nanoparticles [2].
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    A FACILE APPROACH TO SYNTHESIZE GRAPHENE OXIDE AND REDUCED GRAPHENE OXIDE NANOMATERIALS
    (BIT, Sathyamangalam, 2017-08-17) Ramalakshmi V; Yuvashree S; Balavijayalakshmi J
    Technology research in nanotechnology promises breakthroughs in areas such as materials and manufacturing nanoelectronics, medicine, healthcare, energy, biotechnology, information technology, and national security. One of the crucial bottlenecks for the application of graphene-based systems in materials science is their mass production. Meeting the requirements, graphene oxide (GO) has been considered widely as a prominent precursor and a starting material for the synthesis of this processable material [1]. This work describes the synthesis and characteristic analysis of Graphene oxide (GO) and reduced graphene oxide. Graphene Oxide (GO) is synthesized in large quantity from Natural Flake Graphite (NFG) by modified Hummer’s method. The synthesized GO is chemically reduced to Reduced Graphene Oxide (RGO) using hydrazine monohydrate as reducing agent via wet chemical method. The synthesized samples are characterized using Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction analysis (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDS). The characterized samples have been tested for the removal of dye from water in water purification process.
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    ELECTROCHEMICAL BEHAVIOUR OF PREPARED REDUCED GRAPHENE OXIDE/ CHITOSAN NANOCOMPOSITES
    (Sastra University, Thanjavur., 2017-02-27) Yuvashree S; Balavijayalakshmi J
    Recently, efforts have been made to develop technologically feasible graphene-based devices. The development of composite materials based on graphene and natural polymers provides an ideal material in the biomedical field. However, the lack of good mechanical and thermal properties limits its applications. This drawback could be overcome by the reduction of graphene oxide into reduced graphene oxide (RGO). The RGO combined with the polymer helps to increase the conductivity of nanocomposites which thereby enhances the properties of the material to suit commercial applications. This present work is based on the investigation of the electrochemical behaviour of reduced graphene oxide/Chitosan nanocomposite synthesized by chemical reduction method. The synthesized rGO/CS nanocomposites are characterized using ultraviolet–visible (UV-Vis) spectral analysis, Fourier transform infrared (FT-IR) spectral analysis, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis. The surface charge as well as stability of the nanocomposites is examined by electrochemical characterization using cyclic voltammetry technique. The analytical responses and the redox mechanisms are evaluated which shows high current response for RGO/Chitosan nanocomposites compared to pure RGO nanosheets. This suggests that RGO/Chitosan nanocomposites have excellent electrochemical behaviour and is further applied for bio sensing applications.
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    STRUCTURAL AND MORPHOLOGICAL INVESTIGATION ON THE GRAPHENE OXIDE NANOSHEETS FUNCTIONALIZED TRIMETALLIC NANOPARTICLES
    (Vizhi Chudar Pathippagam / Anna University, Chennai, 2017-01-06) Ramalakshmi V; Balavijayalakshmi J
    In recent years, the trimetallic nanoparticles (NPs) are of having great interest because of their novel properties and applications. Trimetallic nanoparticles have improved physicochemical properties compared to their monometallic nanoparticles. Among the other metallic NPs, trimetallic NPs possess scientific and industrial importance because of their unique properties namely, magnetic, optical, electronic, and catalytic for practical applications [1]. In the present paper, the attempt has been made to synthesize trimetallic Au-Ag/Ni nanocomposites on β-cyclodextrin functionalized reduced nano graphene sheets (β-CD-NGS) as the platform. Graphene, a two-dimensional structure consists of sp2 hybridized carbon closely packed honeycomb lattices. It is considered as a basic building block for graphitic materials with all other dimensionalities [2]. It has considerable heed on both the experimental and theoretical fields because of its unique nanostructure and a variety of attracting thermal, mechanical, electrical properties. Based on these remarkable properties of graphene, these graphene nanosheets can be used as an ideal building block for nanocomposites and are broadly applied in many technological fields such as nanophotonics, sensors, catalysis, and supercapacitors [3]. But during the reduction process of graphene oxide (GO) to nano graphene sheets (NGS), NGS tends to agglomerates via Vander Waals interactions, due to the loss of oxygen containing functional groups in GO, and it is difficult for many potential applications. To overcome this problem, the β-Cyclodextrin (β-CD) is introduced into the graphene oxide before the reduction process is fully completed. The introduced β -CD onto the surface of NGS prevents the agglomeration of the NGS and improves the solubility of the β-CD-NGs in water [3]. This new composite have individual properties of two materials, such as large surface area and high conductivity of GO and supramolecular recognition and enrichment capability of β-CD. It is a macrocyclic allied oligosaccharides composed of seven glucose units. It is toroidal in shape with a hydrophobic inner cavity and a hydrophilic exterior which provides water solubility. The characteristic of β-CD facilitates them to selectively bind various organic, inorganic, and biological guest molecules into their cavities to form stable host guest inclusion complexes and also exhibits high molecular selectivity and enantioselectivity. Therefore, β-CD functionalized NGS are used as a platform for the preparation of nanocomposites [4]. In recent years metal nanoparticles (Au, Ag) have been used for many potential applications, because of their high surface to volume ratio and good catalytic activity compared to their respective bulk metals. The noble metals (Au, Pd, Pt etc.) doped with non-noble metals (Fe, Co, Ni etc.) is an admirable approach to intensify the catalytic activity and the sensitivity of nanomaterials [5]. The synthesized nanocomposites are characterized using UV-Vis, FT-IR, XRD, EDX and SEM analysis. Synthesized Pure NGS, β-CD, β-CD-NGS and β-CD-NGS-(Au-Ag/Ni) nanocomposites are characterized using UV-Vis spectroscopy. According to the UV-Vis spectral analysis, the absorption band for pure NGS are obtained around 240 nm and 300 nm for π-π* transition of the atomic C-C bonds and n-π* transitions of aromatic C-C bonds respectively and for β –CD the major peak observed around 260 nm. In the β-CD-NGS spectra, an absorption peak at 260 nm is observed, indicating the successful synthesis of β-CD-NGS. The UV-Vis spectra of β-CD-NGS-(Au-Ag/Ni) nanocomposite confirm the presence of all formed composites [3]. FT-IR spectra of pure NGS, β-CD, β-CD-NGS and β-CD-NGS-(Au-Ag/Ni) nanocomposites are recorded. From the results, the transmission bands of pure NGS obtained around 1100 cm-1, 1600 cm-1 and 3400 cm-1 may correspond to the bending vibrations of coupled C–C/C–O, O–H and O–H stretching vibration respectively. The FT-IR spectra of β-CD-NGS exhibits spectra for β-CD around 940 cm-1, 700 cm-1 and 570 cm-1 may due to the skeletal vibration and pyranose ring vibrations respectively, which is in good agreement with the pure β-CD spectrum. The main absorption peaks of pure NGS are also observed and it confirms the presence of β-CD molecules on the surface of GNS. The FT-IR spectra of β-CD-NGS-(Au-Ag/Ni) nanocomposites also confirm the presence of all the functional groups of synthesized nanocomposites [6]. The crystalline nature of the synthesized nanocomposites is studied using XRD analysis. By observing the sharp crystalline XRD peaks, the formation of pure nanoparticles without any impurities are confirmed .The microstructure of the Pure NGS, β-CD, β-CD-NGS and β-CD-NGS-(Au-Ag/Ni) nanocomposites are investigated by SEM analysis. In the SEM image of β-CD-NGS-(Au-Ag/Ni) nanocomposites, the bright spots are observed, which confirms the formation of trimetallic nanoparticles on CD-NGS [4]. The EDX spectrum of the prepared β-CD-NGS-(Au-Ag/Ni) nanocomposites confirms the presence of the β-CD, NGS, Au, Ag, Ni element in the prepared nanocomposites [7]. The as-synthesized nanocomposites may have many potential applications in removal of dye pollutants and waste water treatment technologies etc.