THE UNUSUAL ADSORPTION STATES OF PT(111) ELECTRODES STUDIED BY AN IODINE DISPLACEMENT METHOD - COMPARISON WITH AU(111) ELECTRODES

The process of iodine adsorption on Pt(lll) and Au(lll) electrodes is utilized to identify the nature of unusual adsorption states on the Pt(lll) electrode. The application of iodine allows the adsorbate replacement measurements at higher potentials than it has previously been practised with CO, thus enabling the study of Pt(lll) in perchloric acid medium. The comparison between the results obtained with the two probes leads to self-consistency of the previous and present results. The data obtained with the two electrodes (and in the two supporting electrolytes) are mutually consistent. In sulphuric acid, we confirm that adsorption of an anion (sulfate or bisulfate) accounts for the unique features of the Pt(lll) voltammetry. We also provide experimental results for identifying the origin of the unusual adsorption states in perchloric acid solution.