Nanocomposites of size-controlled gold nanoparticles and graphene oxide: formation and applications in SERS and catalysis.

In this paper, we describe the formation of Au nanoparticle-graphene oxide (Au-GO) and -reduced GO (Au-rGO) composites by noncovalent attachment of Au nanoparticles premodified with 2-mercaptopyridine to GO and rGO sheets, respectively, viaπ-π stacking and other molecular interactions. Compared with in situ reduction of HAuCl4 on the surface of graphene sheets that are widely used to prepare Au-GO composites, the approach developed by us offers well controlled size, size distribution, and morphology of the metal nanoparticles in the metal-GO nanohybrids. Moreover, we investigated surface enhanced Raman scattering (SERS) and catalysis properties of the Au-graphene composites. We have demonstrated that the Au-GO composites are superior SERS substrates to the Au NPs. Similarly, a comparative study on the catalytic activities of the Au, Au-GO, and Au-rGO composites in the reduction of o-nitroaniline to 1,2-benzenediamine by NaBH4 indicates that both Au-GO and Au-rGO composites exhibit significantly higher catalytic activities than the corresponding Au nanoparticles.