JAQUELINE JAMARA SOUZA SOARES
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Resumo IPEN-doc 25329 Synthesis and characterization of magnetic graphene oxide nanocomposites2018 - TOMINAGA, F.K.; SAKATA, S.K.; SOARES, J.J.S.; JACOVONE, R.M.S.Graphene oxide (GO) is a unique material that can be described as a single monomolecular layer of graphite containing various oxygen functionalities such as epoxide, carbonyl, carboxyl and hydroxyl groups. Chemical modifications at the surface of the graphene oxide through the incorporation of magnetite can provide magnetic properties to these nanomaterials. This work aims to synthesize and characterize graphene oxide/magnetite (GO/M) nanocomposites, evaluating the different proportions of incorporated magnetite. The synthesis of graphene oxide/magnetite nanocomposites was performed by co-precipitation of iron salts on the graphene oxide (GO) particles in alkaline medium. The characterization of the nanocomposites was performed by thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), X-ray diffraction (XRD), nanoparticle tracking analysis (NTA) and scanning electron microscopy (SEM). The thermogravimetric results showed the incorporation of approximately 20, 50, 70 and 80% of magnetite to the graphene oxide. Regarding the hydrodynamic size, for the magnetite, mode values of 31.3 ± 1.3 nm were determined, whereas for the GO/M, the mode values of size ranged from 72.8 to 194 nm. The results of XRD and FTIR showed the respective characteristic diffraction and absorption peaks only for graphene oxide, magnetite and GO/M(20%). It was not observed characteristic peaks for the other samples of graphene oxide that have higher loads of magnetite incorporated.Resumo IPEN-doc 24844 Sustainable synthesis of transition metals/graphene oxide nanocomposites by electron beam irradiation2017 - SAKATA, S.K.; SOBRINHO, L.F.; JACOVONE, R.M.S.; SOARES, J.J.S.; TOMINAGA, F.K.; ANGNES, L.; GARCIA, R.H.L.Graphene is nanomaterial with unique physical and chemical properties that makes it a precursor for the synthesis of new materials, such as conductive nanocomposites. Graphene can be obtained by the reduction of graphene oxide, but when it is incomplete, reduced graphene oxide (rGO) is produced with both graphene and graphene oxide properties: it is electrical and thermal conductor, it can be exfoliated in several polar solvents and moreover, the oxygen groups can later be functionalized, affording nanocomposites for electrochemical applications and also in biomaterials. A method of increasing the electrical conductivity of graphene-based compounds is by the incorporation of metallic nanoparticles. When these nanomaterials are joined together the surface area increases for the passage of electric current and the electrical conductivity. The chemical reduction method for the incorporation of metallic nanoparticle on GO involves toxic reagents or it is a time-consuming and it also requires high costs for the removal of excess reagents and by-products. The general synthesis of transition Metal/graphene-based nanocomposites by the electron beam in a sustainable process will be presented. The experiments were performed in a 1.5 MeV electron accelerator at room temperature and no hazardous wastes were generated. The nanocomposites were characterized by FT-IR, DRX and TEM/EDS as metallic nanoparticle at the average size of 5-20 nm incorporated into reduced graphene oxide layers. The electrochemical behavior of these nanocomposites was evaluated by cyclic voltammetry.