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Item SYNTHESIS AND CHARACTERIZATION OF GRAPHENE OXIDE BASED METAL NANOCOMPOSITES(Royal Book publishers / PSGR Krishnammal College for Women, Coimbatore, 2018-01-03) Yuvashree S; Balavijayalakshmi J; Sharvasri SGraphene, a monolayer of carbon atoms packed into a dense honeycomb crystal structure has attracted considerable attention and numerous investigations because of its unique nanostructure and its extraordinary properties. 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. In this present work, metal nanoparticles are decorated onto the graphene surface which helps to increase the conductivity of nanocomposites and enhances the properties of the material. Thus graphene based metal nanocomposites are prepared by chemical reduction method. 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). XRD reveals that the product is well crystallized. Thus the prepared nanocomposites can be applied for biomedical applications.Item GRAPHENE BASED NANOCOMPOSITES FOR ELECTROCHEMICAL DETECTION OF H2O2(Royal Book publishers / PSGR Krishnammal College for Women, Coimbatore., 2018-01-01) Yuvashree S; Balavijayalakshmi JIn this study, a novel reduced graphene oxide-based nanocomposite electrochemical biosensor for the reliable detection of H2O2 is developed. Reduced graphene oxide-chitosan nanocomposites are successfully prepared by chemical reduction method. XRD, FT-IR, SEM and EDAX analysis are performed to characterize the structural, spectral, morphology and composition of the prepared nanocomposites. The response of the modified electrode to H2O2 is examined by cyclic voltammetry. Under optimal experimental conditions, the RGO-CS biosensor showed outstanding catalytic activity toward H2O2 reduction. The H2O2 reduction peaks are observed about 0.1V. These results confirm that RGO-CS nanocomposites with the high surface area and electrocatalytic activity offer a promising candidate for the detection of H2O2 in biological environment.Item A FACILE APPROACH TO SYNTHESIZE GRAPHENE OXIDE AND REDUCED GRAPHENE OXIDE NANOMATERIALS(BIT, Sathyamangalam, 2017-08-17) Ramalakshmi V; Yuvashree S; Balavijayalakshmi JTechnology 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.Item ELECTROCHEMICAL BEHAVIOUR OF PREPARED REDUCED GRAPHENE OXIDE/ CHITOSAN NANOCOMPOSITES(Sastra University, Thanjavur., 2017-02-27) Yuvashree S; Balavijayalakshmi JRecently, 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.Item A FACILE SYNTHESIS OF REDUCED GRAPHENE OXIDE/CHITOSAN/AG NANOCOMPOSITES(Vizhi Chudar Pathippagam / Anna University, Chennai., 2017-01-06) Yuvashree S; Balavijayalakshmi JGraphene is a monolayer of carbon atoms, which is densely packed in a honeycomb lattice. Owing to its two-dimensional (2D) nanostructure, it has attracted enormous attention in the field of nanotechnology. Due to its unique catalytic, magnetic, optoelectronic and biological properties, Graphene and its derivatives has exhibited extensive and potential applications in electrode modifying materials, sensors, biomedical, bioengineering, drug delivery, gene delivery and semiconductors [1]. Chitosan (CS) is a natural bio polysaccharide and the most abundant polymer which is biocompatible and can be degraded by enzymes in human body. It has attracted considerable interest due to its biodegradability, biocompatibility, non-toxicity, good water permeability, high mechanical strength, adhesion and antibacterial properties, which leads to tremendous applications in agriculture, biopesticide, wine making, polyurethane coating, medicine etc., [2]. In addition to these, metal nanoparticles have been widely used for the fabrication of nanocomposites. Silver (Ag) nanoparticles, a well known and most popular, have also been used for long time in research areas because of its excellent chemical and physical properties. It has been applied in antimicrobial coatings, textiles, keyboards, wound dressings, and biomedical applications such as drug delivery, antibacterial etc. These biomedical devices now contain silver nanoparticles that continuously release a low level of silver ions to provide protection against bacteria. In this present work, reduced graphene oxide/Chitosan/Ag nanocomposites have been synthesized by chemical reduction method. Graphene Oxide (GO) is obtained from natural graphite powder according to a modified Hummers method, in which graphite is treated with a mixture of very strong oxidizers such as sulphuric acid, sodium nitrate and potassium permanganate. The carbon atoms in GO loses the electrical conductivity nature of graphene and it can be restored by reduction of GO into reduced graphene oxide (rGO). This is then followed by synthesizing rGO/CS, rGO/CS/Ag nanocomposties [3]. Thus the prepared GO, rGO, rGO/CS, rGO/CS/Ag nanocomposites is further 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. It is observed from UV-Vis spectral analysis that the absorption spectra for GO has two characteristic peaks around 230 nm and 301nm due to π-π* transition of aromatic C=C bonds and n-π* transition of C=O bonds respectively. On further reducing GO, the peak gets shifted around 265 nm and the peak around 301nm gets disappeared, which confirms the reduction of GO into rGO [4]. A new peak formed around 430 nm indicates the formation of rGO/CS/Ag nanocomposites. FT-IR spectral analysis confirms the functional groups of the as-obtained GO, rGO, rGO/CS/Ag nanocomposites. The FT-IR spectra is observed in the region of 4000 to 400 cm-1.The absorption band around 3500 cm-1 attributes to O-H stretching vibrations due to hydroxyl groups in GO. The band around 1720 cm-1 indicates the –COOH vibrations, which shows the reduction of GO into rGO and the C-H stretching vibrations are assumed to be around 2854 cm-1. The band around 1680 cm-1 indicates the presence of acetyl amino groups and C=C stretching vibration is observed around 1387 cm-1[5]. The crystalline structure of the prepared GO, rGO, rGO/CS/Ag nanocomposites is confirmed by X-ray diffraction (XRD) analysis. The diffracted peak formed corresponds to the (002) plane of GO which exhibits inter-planner spacing of 0.80±3nm. On further adding CS and Ag nanoparticles, the diffraction peak of GO reduces and simultaneously the diffraction peak of Ag increases. RGO/CS/Ag nanocomposites shows diffraction peak for rGO, CS and Ag. The morphological studies have been carried out using Scanning Electron Microscope [6]. It indicates that CS/Ag nanocomposites are uniformly dispersed on to the rGO nanosheets. Thus the prepared rGO/Chitosan/Ag nanocomposites can be tested for biomedical applications [7].