I n s i t u scanning tunneling microscopy of platinum (111) surface with the observation of monatomic steps

I n situ scanning tunneling microscopy was applied to single-crystal platinum (111) surfaces both before and after electrochemical potential cycling in an aqueous sulfuric acid solution. Steps observed on a Pt(111) facet were usually located on nearly parallel straight lines or on the directions forming an angle of close to 60°, as expected for a surface with threefold symmetry. The height of each step was in accord with the monatomic step height of 0.238 nm on the Pt(111) surface. Randomly oriented islands a few atoms in height were clearly observed on the terraces after five potential cyclings. It was suggested that Pt adatoms produced by the reduction of the oxide are coagulated on the terraces.