Siberian Federal University

The products of the reduction of chloroauric acid by aqueous sulfide ions immobilized onto highly oriented pyrographite (HOPG) have been studied by scanning probe microscopy, electron microscopy, X-ray photoelectron and optical absorption spectroscopy. The gold nanoparticles (Au NPs), including tabular ones, formed at initial S/Au ratios of 0.5 – 1.2 have poor adhesion to the inert HOPG surfaces. With increasing the content of sulfide, the quantity of Au NPs, which nucleate in the solution, decreases, while nanostructured films more easily deposit on HOPG from liquid or amorphous intermediates of the gold reduction. The main end products are metallic Au NPs capped with polysulfide-type species and, at a high sodium sulfide content, amorphous gold sulfide.