Sonolytic Design of Graphene-Au Nanocomposites. Simultaneous and Sequential Reduction of Graphene Oxide and Au(III)

High-frequency ultrasound at 211 kHz is effective in developing graphene-based nanoarchitectures. Both simultaneous and sequential reduction steps have been employed to reduce the graphene oxide (GO) and a gold precursor, HAuCl4. Characterization of the composites by transmission electron microscopy following the reduction process revealed well-dispersed Au nanoparticles on the reduced GO (RGO) sheets that are no more than a few layers thick (1-4 layers). The Raman spectra of the RGO Au composites showed a distinct surface enhancement of the graphene Raman bands upon increasing the surface coverage of gold nanoparticles. The merits of sonolytic reduction in developing graphene-based composites are discussed.