A general and efficient method for decorating graphene sheets with metal nanoparticles based on the non-covalently functionalized graphene sheets with hyperbranched polymers

Multipyrene terminated hyperbranched polyglycidol (mPHP) has been synthesized and used to non-covalently functionalize pristine graphene sheets (GSs) through pi-pi stacking interactions. Mediated by the mPHP layer, a variety of metal nanoparticles (Au, Ag and Pt) were in situ generated and deposited onto the surface-modified GS, yielding versatile GS/mPHP/metal nanohybrids. As typical examples, by simply controlling the concentration of HAuCl4 used, Au nanostructures ranging from isolated spheres to a continuous film were created and coated onto the surface-modified GS. The studies on the fluorescence properties of resulting GS/mPHP/Au hybrid nanostructures reveal that the GS and controllable content of Au components in the hybrids can effectively quench the fluorescence emission of mPHP in a controlled manner. Further investigation indicates that GS/mPHP/Au hybrids are promising surface enhanced Raman scattering (SERS) substrates. The SERS activities of these hybrids depend on the contents and form of the Au. The GS/mPHP/Au hybrid containing continuous Au films exhibits the strongest SERS activity. GS/mPHP/Au hybrids are also used as efficient heterogeneous catalysts for the reduction of 4-NP, and demonstrate excellent catalytic performance. The detailed reaction kinetics and the reusability of such catalysts have also been investigated.