Reconstruction of Vicinal Pt(111) Surfaces Influenced by Step Orientations under High Pressures of C2H4 and CO

The structures of two stepped Pt crystal surfaces, Pt(332) and Pt(557), were studied at high gas pressures at room temperature by high-pressure STM and ambient-pressure XPS. These crystals posses the same type of terraces but different types of steps. HP-STM shows that the two crystal surfaces respond differently to the exposure of 0.5 Torr of ethylene. Furthermore, after stabilizing the two crystals under 0.5 Torr of CO to form clusters, a subsequent introduction of 0.5 Torr of ethylene can remove the clusters and restore the stepped structure on Pt(332), whereas the CO-induced clusters remain on Pt(557). AP-XPS experiments were performed by following the same procedures to account for the phenomena. The step orientation is crucial in influencing the surface restructuring processes at high gas pressures.