Metal/Functionalized Graphene Nanocomposites:Synthesis,Characterization And Application

In this paper,the thiophenol functionalized graphene(TP-GS)has been synthesized via a facile,one-pot synthetic approach.We fabricated this functionalized graphene by attaching 4-aminophenol to the graphene sheets via covalent bonds.The resulted TP-GS is the key of the two works as follows.The first part is about Au nanoparticles self-assembled on thiophenol functionalized graphene(Au/TP-GS).We use a facile,synthetic approach to synthesize the new material.The details of the morphologies,size and dispersion of the Au nanoparticles(NPs)and the chemical composition of the novel catalyst was verified by systematic characterizations,including transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM),Raman spectroscopy,X-ray diffraction(XRD)and X-Ray photoelectron spectroscopy(XPS).The resulting Au/TP-GS exhibited excellent catalytic activity for both the reduction of 4-nitrophenol and the photodegradation of rhodamine B due to the synergistic effects between the TP-GS and Au NPs and the high utilization of the metal.The practical and efficient nanocatalyst synthesized by a facile in-situ reduction approach,provides more environmentally benign synthesis route to effectively produce low cost Au-based catalysts.The second part is about hollow nanosphere with an ultrathin PdAu alloy shell on thiophenol-functionlized graphene for electrooxidation of methanol.In this part,a hollow PdAu alloy nanostructure with an ultrathin shell(2-3 nm)has been successfully synthesized via a one-pot synthesis process and then assembled on thiophenol-grafted graphene sheets by strong coordination bonds.The resulting hollow alloy nanospheres and the 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,scanning electron microscope(SEM)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 methanol was also explored.The hollow PdAu alloy nanospheres,especially the graphene-supported nanocomposites,exhibited striking electrocatalytic activities which show potential application in fuel cells.