The structural evolution of a Pt surface with 0.4 monolayer sub-surface Fe on annealing in 1.1 x 10−7kPa O2 was studied by scanning tunnelling microscopy and X-ray photo-electron spectroscopy. When the annealing temperature was 600 K, only dissociative adsorption of O2 occurred, which induced the local restructuring of surface regions. At 750 K, subsurface Fe atoms segregated onto the surface and were oxidized. When the annealing temperature was increased to 850 K, well-defined monolayer FeO islands with periodic arrays of defects were formed. The defects were located at the hexagonal closest packed sites (face-centered cubic) of FeO moiré unit cells and were either single oxygen vacancies or multiple oxygen vacancies consisting of six missing O atoms. The formation of periodic defects on monolayer FeO islands might be a way to construct active sites on Pt-Fe model catalysts.

Formation of Periodic Arrays of O Vacancy Clusters on Monolayer FeO Islands Grown on Pt(111). T.Ma, Q.Fu, Y.Yao, Y.Cui, D.Tan, R.Zhai, X.Bao: Chinese Journal of Catalysis, 2010, 31[8], 1013-8