In situ scanning tunnelling microscopy of a platinum {111} surface in aqueous sulphuric acid solution

Abstract

An in situ scanning tunnelling microscope was applied, for the first time, to a single-crystal platinum {111} surface both before and after electrochemical potential cycling in aqueous sulphuric acid solution. The single-crystal Pt{111} was annealed in a flame near 1100 °C for 1 min and then quickly brought into contact with pure water. It was not possible to see any particular structures on the fire-annealed single crystal. It is shown that the fire-annealing procedure can produce an almost completely atomically flat surface on a single crystal. The flat {111} surface of the Pt crystal was roughened by the electrochemical potential cycling. Semi-spherical domains have predominantly been observed on the single crystal. These domains seem to be randomly distributed over the surface. The diameter and height of the semi-spherical domains were in the ranges 20–30 and 5–10 A, respectively.