Scanning tunnelling microscopic investigation of iodine-covered Pt single-crystal electrodes

Abstract

Using a home-built scanning tunnelling microscope (STM), the structure of iodine adlayers in air and in electrolyte has been investigated. In air, the occurrence of tip-adatom interactions was demonstrated and an antiphase domain boundary was resolved atomically. The adlayer structure on the Pt(100) surface in 10^–4mol dm^–3 I^– solution (pH 4) is potential dependent. At 0.75 V vs. RHE the Pt(100)([graphic omitted] × 5[graphic omitted])R45°–I adlattice is found. At 0.5 V, domains of this structure and of a Pt(100)([graphic omitted] × [graphic omitted])R45°–I adlattice exist. Desorption of iodine (at 0.25 V) leads to a hexagonally reconstructed surface. During deposition of small amounts of copper onto the iodine-covered surface, islands with diameters between 10 and 30 Å, which are one to three atomic layers high, are formed first and then coalesce to a hill-like structure.