Electrodeposited thin mercury films on Pt-Ir alloy electrodes

Mercury thin films prepared by electrochemical deposition on Pt-Ir alloy an d after partial removing of mercury at different temperatures were studied by means of an interferometric surface mapping microscope and by X-ray phot oelectronic spectroscopy. Mercury film samples having mercury partially rem oved by anodic stripping at a potential more positive than the correspondin g peak in the voltammogram were also studied using the same techniques. For blank samples the surface topographic studies showed well defined grain bo undaries. Mercury film samples when heated up to different temperatures sho wed as material is removed and that the surface roughness decreases as the temperature increases. For samples heated up to 800 degrees C the surface r oughness is approximately the same that for the blank. A model for the inte rphase of volumetric mercury electrodeposited on a Pt-Ir alloy has been pro posed using samples both electrochemically and thermally removed of their H g coatings. The model includes a layered three-region structure, containing at least two Pt-Hg intermetallics: PtHg4 and PtHg2. A substrate modified r egion, iridium rich, has also been detected. (C) 1999 Elsevier Science S.A. All rights reserved.