Browsing by Author "Khamlich, S."

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    Growth of graphene underlayers by chemical vapor deposition
    (AIP Publishing, 2013) Fabiane, M.; Khamlich, S.; Bello, A.
    We present a simple and very convincing approach to visualizing that subsequent layers of graphene grow between the existing monolayer graphene and the copper catalyst in chemical vapor deposition (CVD). Graphene samples were grown by CVD and then transferred onto glass substrates by the bubbling method in two ways, either direct-transfer (DT) to yield poly (methyl methacrylate) (PMMA)/graphene/glass or (2) inverted transfer (IT) to yield graphene/PMMA/glass. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to reveal surface features for both the DT and IT samples. The results from FE-SEM and AFM topographic analyses of the surfaces revealed the underlayer growth of subsequent layers. The subsequent layers in the IT samples are visualized as 3D structures, where the smaller graphene layers lie above the larger layers stacked in a concentric manner. The results support the formation of the so-called �inverted wedding cake�stacking in multilayer graphene growth.
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    Hydrothermal synthesis of simonkolleite microplatelets on nickel foam-graphene for electrochemical supercapacitors
    (J. Solid State Electrochem, 2013) Khamlich, S.; Fabiane, M.; Bello, A.
    Nickel foam-graphene (NF-G) was synthesized by chemical vapour deposition followed by facial in situ aqueous chemical growth of simonkolleite (Zn5(OH)8Cl2�H2O) under hydrothermal conditions to form NF G/simonkolleite composite. X-ray diffraction and Raman spectroscopy show the presence of simonkolleite on the NF-G, while scanning and transmission electron microscopies show simonkolleite micro-plates like structure evenly distributed on the NF-G. Electrochemical measurements of the composite electrode give a specific capacitance of 350 Fg?1 at current density of 0.7 Ag?1 for our device measured in three-electrode configuration. The composite also shows a rate capability of ~87 % capacitance retention at a high current density of 5 Ag?1 as an electrode material for supercapacitor applications, which makes it a promising candidate