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Single- and few-layer graphene sheets were fabricated by selective chemical reactions between Co film and SiC substrate. A rapid cooling process was employed. The number of layers and crystallinity of graphene sheets were controlled by process parameters. The formation mechanism of graphene was highly sensitive to carbon diffusion. Free carbon precipitated and then moved across the product layer that was composed mainly of cobalt-silicides. The graphene layer formed homogeneously on the surface and then transferred to the other substrate. This could provide a method for high-quality fabrication of wafer-sized graphene sheets.

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Here we prepared three reduced graphene oxides-hydrazine and H 2 /Ar reduced graphene oxide at 200 and 500 C (RGO-N, RGO-H-200 and RGO-H-500) with almost identical Brunauer-Emmett-Teller (BET) surface areas to study the effect of functional groups on adsorption behaviors for the removal of methylene blue (MB) from aqueous solution. The maximum adsorption capacities of RGO-N, RGO-H-200 and RGO-H-500 for MB were 159, 91 and 81 mg/g at 283 K, respectively. X-ray photoelectron spectra measurements demonstrated that the content of relevant functional groups in three adsorbents differs from each other. The C O or C N double bonds are able to couple with the C C/C C bonds to form a large conjugate structure, enhancing the interactions between RGO and MB molecules. While, the C OH bonds contribute little, if any, to the increase of adsorption efficiency because of the steric hindrance towards benzene-ring containing dye molecules.

We report a method to realize the H2 production and graphene-oxide (GO) reduction simultaneously over GO/SiC composite under visible light irradiation with KI as sacrifice reagent. The weight content of GO is regulated in the reaction system. The rate of H2 production reaches to 95 μL/h with 1% GO content in GO/SiC composite system, which is 1.3 times larger compared to the case in pure SiC NPs under visible light. The reduced-GO sheet can serve as an electron collector and transporter to efficiently separate the photo-generated electron-hole pairs, lengthening the lifetime of the charge carriers effectively.