| Abstract
| - Spectroelectrochemical experiments and density functional theory (DFT) based calculations are combined toelucidate the nature of the species adsorbed when a perchloric acid solution saturated with carbon dioxide isin contact with well-defined electrode surfaces. Previous results reported for the Pt(111) electrode are revisedand completed with new data for a palladium monolayer deposited on the Pt(111) electrode. From the DFTcalculations and from the potential and pH dependent behavior of the main adsorbate vibrational bands, it issuggested that, for potentials below 0.65 V, bicarbonate species are adsorbed at the Pt(111) electrode surfacein a short-bridge bidentate configuration. At higher potentials, the adsorbate adlayer is completed by theformation of adsorbed carbonate also in a short-bridge configuration. The ratio between the surface coveragesof adsorbed bicarbonate and carbonate depends on both the electrode potential and the solution pH. Adsorbedbicarbonate prevails at the palladium monolayer irrespective of the electrode potential. This behavior, togetherwith a concomitant lower adsorbate coverage, can be related to the competitive adsorption of hydroxylatedspecies.
|
