Synthesis and Characterization of Gold/Polypyrrole Core−Shell Nanocomposites and Elemental Gold Nanoparticles Based on the Gold-Containing Nanocomplexes Prepared by Electrochemical Methods in Aqueous Solutions

We report here the first electrochemical pathway to prepare Au-containing nanocomplexes with the mean diameter of 2 nm in 0.1 N KCl aqueous solutions without addition of any stabilizer. Encouragingly, polypyrrole- (PPy-) coated gold nanocomposites with a core−shell structure and a diameter smaller than 8 nm can be prepared by the formation of self-assembled monolayers and further orderly autopolymerization of pyrrole monomers on these nanocomplexes. The prepared Au/PPy nanocomposites should exhibit extremely high conductivity, as indicated by the analyses of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and surface-enhanced Raman scattering (SERS). Meanwhile, elemental Au(0) nanoparticles of a mean diameter of 5 nm can be obtained by treating the Au/PPy-nanocomposites-containing solution with sonification.