In-situ STM study of phosphate adsorption on Cu(111), Au(111) and Cu/Au(111) electrodes

Christian Schlaup, Sebastian Horch

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Abstract

The interaction of Cu(111), Au(111) and Cu-covered Au(111) electrodes with a neutral phosphate buffer solution has been studied by means of cyclic voltammetry (CV) and in situ electrochemical scanning tunneling microscopy (EC-STM). Under low potential conditions, both the Cu(111) and the Au(111) surface appear apparently adsorbate free, indicated by the presence of a (4×4) structure and the herringbone surface reconstruction, respectively. Upon potential increase, phosphate anions adsorb on both surfaces and for Cu(111) the formation of a (√3×√3)R30° structure is found, whereas on Au(111) a "(√3×√7)" structure is formed.
For a Cu-submonolayer on Au(111), coadsorption of phosphate anions leads to the formation of a (2×2) vacancy structure within an assumed pseudomorphic structure of the Cu-submonolayer with the phosphate anions occupying the vacancies. When desorbing the phosphate anions at low potentials, the Cu-submonolayer first becomes mobile and eventually undergoes an irreversible transition to a coalescent nonpseudomorphic structure.
Original languageEnglish
JournalSurface Science
Volume608
Pages (from-to)44-54
ISSN0039-6028
DOIs
Publication statusPublished - 2013

Keywords

  • Scanning tunneling microscopy
  • Electrochemical phenomena
  • Catalysis
  • Copper
  • Phosphate
  • Carbon dioxide

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