STRUCTURAL EFFECTS ON ETHINE ADSORPTION AT GOLD SINGLE-CRYSTAL ELECTRODES

The adsorption of ethine at +0.60 V versus RHE in 0.1M HClO4 was studied on different gold crystal faces ((111), (110), (100) and (210)) as well as on polycrystalline gold. For all studied surfaces 90% of the adsorbate formed was reduced in the first negative-going potential scan at about +0.25 V versus RHE, except for Au(100) where 50% of the adsorbed species remained on the surface after the first reduction cycle. With respect to oxidation of the adsorbate the crystal faces under investigation displayed distinctive differences. Whereas Au(210) and Au(poly) exhibited only a single voltammetric peak at comparable potentials (approximately 1.30 V), on the other orientations several peaks at potentials differing by about 0.30 V were observed. On Au(111) the lowest oxidation peak potential(1.13 V) as well as the highest onset potential for the electro-oxidation (0.97 V) were found.