Electrochemical scanning tunneling microscopy examination of the structures of benzenethiol molecules adsorbed on Au(1 0 0) and Pt(1 0 0) electrodes

G. Z. Liu, L. Y. Ou Yang, C. H. Shue, H. I. Ma, S. L. Yau, S. H. Chen

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9 Scopus citations

Abstract

In situ electrochemical scanning tunneling microscopy (STM) has been used to examine the structures of benzenethiol adlayers on Au(1 0 0) and Pt(1 0 0) electrodes in 0.1 M HClO4, revealing the formation of well-ordered adlattices of Au(1 0 0)-(√2 × √5) between 0.2 and 0.9 V and Pt(1 0 0)-(√2 × √2)R45° between 0 and 0.5 V (versus reversible hydrogen electrode), respectively. The coverage of Au(1 0 0)-(√2 × √5) is 0.33, which is identical to those observed for upright alkanethiol admolecules on Au(1 1 1). In comparison, the coverage of Pt(1 0 0)-(√2 × √2)R45° - benzenethiol is 0.5, much higher than those of thiol molecules on gold surfaces. This result suggests that benzenethiol admolecules on Pt(1 0 0) could stand even more upright than those on Au(1 0 0). All benzenethiol admolecules were imaged by the STM as protrusions with equal corrugation heights, suggesting identical molecular registries on Au(1 0 0) and Pt(1 0 0) electrodes, respectively. Modulation of the potential of a benzenethiol-coated Au(1 0 0) electrode resulted in irreversible desorption of admolecules at E ≤ 0.1 V (vs. reversible hydrogen electrode) and oxidation of admolecules at E ≥ 0.9 V. In contrast, benzenethiol admolecule was not desorbed from Pt(1 0 0) at potentials as negative as the onset of hydrogen evolution. Raising the potential rendered deposition of more benzenethiol molecules before oxidation of admolecules commenced at E > 0.9 V.

Original languageEnglish
Pages (from-to)247-254
Number of pages8
JournalSurface Science
Volume601
Issue number1
DOIs
StatePublished - 1 Jan 2007

Keywords

  • Adsorption
  • Au(1 0 0)
  • Benzenethiol
  • Pt(1 0 0)
  • Scanning tunneling microscope
  • Solid-liquid interface

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