A widely soluble graphene sheet/Congo red (GSCR) composite was synthesized and applied to prepare GSCR/Au hybrid materials. UV-vis absorption, Fourier transform infrared, Raman, and X-ray photoelectron spectra revealed that Congo red (CR) is successfully coupled on graphene sheets. The morphology of GSCR was studied by transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. The dispersion behavior of the GSCR composite was also studied in 18 different solvents, and the digital images indicate that it is soluble both in water and in a variety of organic solvents. The GSCR nanosheets are still single layers or bilayers in water and individual from one to another after 100 days of storage. Furthermore, the mechanism of GSCR's good solubility was successfully explained by the Hansen solubility parameters. The four standard probe result shows that the GSCR films have a bulk conductivity of approximately 6850 S m(-1). The wide solubility and long lifetime of GSCR solutions are absolutely necessary for further treatment. As an example, Au nanoparticles densely decorated CR-functionalized graphene sheets through electrostatic interaction.

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A novel hollow AuPd (hAuPd) alloy nanostructure with a rough surface was fabricated via a facile onepot simultaneous reduction of Au(III) and Pd(I) and then assembled on ionic liquid-grafted graphene sheets by electrostatic interaction to form graphene-metal hybrid nanomaterials under mild conditions. The resulting hollow alloy nanostructure and graphene nanocomposites were then characterized using many techniques, such as transmission electron microscopy (TEM), high-resolution TEM (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), element analysis mapping, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), confirming that the alloy nanoparticles with hollow cores had been successfully synthesized by one step galvanic replacement and attached firmly onto the graphene sheets. The electrocatalytic ability of the resulting nanocomposites for direct oxidation of formic acid was also explored. The hollow AuPd alloy nanospheres, especially the graphene-supported nanocomposites, exhibited striking electrocatalytic activities which show potential application in fuel cells.