Structure sensitivity of irreversibly adsorbed tin on gold single-crystal electrodes in acid media

Tin adlayers formed on well defined gold electrodes upon irreversible adsorption from Sn-II solutions have been characterized by means of cyclic voltammetry in sulfuric and perchloric acid solutions. The surface redox reactions undergone by the tin adatom have been found to be structure sensitive. From the analysis of the voltammetric charges involved in these processes it can be suggested that adsorbed tin is oxidized to oxygenated Sn-II species, which are stable at the electrode surface as long as the electrode potential is kept below 0.25 V. At higher potentials, soluble Sn-IV species are formed and the adlayer is removed from the electrode surface. The stability of the adlayer is strongly dependent on the solution pH. On Au(111), adsorbed tin is directly oxidized to Sn-IV species.