The adsorption and electropolymerization of terthiophene on Au(1 1 1) electrode – Probed by in situ STM

Chingche Chen, Xin Ping Peng, Shuehlin Yau

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In situ scanning tunneling microscopy (STM) was used to examine terthiophene (TT) adsorbed on an ordered Au(1 1 1) electrode in 0.1 M H2SO4 and HClO4, as a model system to gain a fundamental understanding of the effects of potential control on the coadsorption of anion and the oxidation of a thiophene - bearing entity. TT was irreversibly adsorbed onto an Au(1 1 1) bead crystal from a dosing solution made of ethanol at room temperature. The cyclic voltammogram (CV) recorded with this sample in 0.1 M H2SO4 showed a series of well-defined peaks, resulting from the restructuring of the TT adlayer, coupled with anion coadsorption and the phase transition of the Au(1 1 1) electrode. In contrast, the CV obtained in 0.1 M HClO4 was mostly featureless before TT admolecules were irreversibly oxidized at E > 0.7 V (vs Ag/AgCl). TT molecule was adsorbed most horizontally on Au(1 1 1) electrode in H2SO4, but displaced by bisulfate anion at positive potential. Anodization of this TT/Au(1 1 1) electrode triggered the oxidation and subsequent coupling of TT monomers to yield oligothiophenes, whose internal structures and dimensions were revealed by STM in pH1 and 5 sulfate media. The as – produced oligothiophenes appeared as winding ribbons spanning ∼ 200 and ∼ 40 Å in pH 5 and 1 sulfate media. Their internal structures, particularly the trans and cis conformations of neighboring thiophenes units, were visualized by molecular resolution STM.

Original languageEnglish
Article number116651
JournalJournal of Electroanalytical Chemistry
StatePublished - 15 Sep 2022


  • in situ STM
  • Molecular adsorption
  • Oligothiophene
  • Ordered Au(1 1 1) electrode
  • Terthiophene


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