THE UNDERPOTENTIAL DEPOSITION OF COPPER ON PT(311) - SITE-SELECTIVE DEPOSITION AND ANION EFFECTS

The underpotential deposition of copper on Pt(311) = Pt[2(111) x (100)] stepped surfaces has been studied, and the results are compared with those for the same processes on Pt(111) and Pt(100). We find that the adsorption/desorption of copper on the (111) (terrace) and (100) (step) sites of this surface takes place at different potentials so that selective adsorption on terrace or step sites is possible. The potentials, and their relative position, are different from those on Pt(111) and Pt(100) surfaces. These differences are ascribed to competitive effects from the anions which adsorb more strongly on the (100) than on the (111) sites. In addition, the presence of halides (Cl-, Br-) dramatically affects the electrodeposition process.