Unraveling the electronic structure of cobalt oxide nanoislands on Au(111)

This study utilizes spatially resolved low temperature scanning tunneling microscopy and spectroscopy to investigate cobalt oxide nanoislands on Au(111) single crystal surfaces. The electronic structure of bilayer, trilayer and multilayer islands is measured, and the findings are correlated with structural variations across the islands, at oxygen defect lines on the islands and at the island step edges. Of particular importance is the identification of electronic features below the Fermi level unique to certain island edges, that are well-known to exhibit increased chemical reactivity. The results advance the understanding of the electronic properties of surface supported cobalt oxide nanostructures, which are known to be important for catalytic applications. Furthermore, on the trilayer island structures a distinct peak in the density of states at the Fermi level is measured that adds to theoretical predictions of superconductivity in CoO2 layers.