Measurement of adsorption rates of anions on Au(111) electrodes by impedance spectroscopy

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Abstract

We have measured impedance spectra on Au(111) electrode in aqueous perchlorate solutions containing specifically adsorbing anions (SO42-, Cl-, Br- and I-) of about 10-4 M concentrations at potentials where the dominant electrode process is the adsorption of the above anions. Accordingly, the impedance spectra have been analyzed in terms of the Frumkin-Melik-Gaykazyan adsorption impedance theory. With SO42-, Cl- we found the adsorption rates to be immeasurably high; with Br- and I- the apparent rate coefficients could be determined. For the halide anions this quantity increases in the order of Cl- > Br- > I-; and rapidly decreases with increasing electrode potential and coverage. We attribute this change to the decrease of the occupancy related hindrance factor overcompensates the increase of the rate coefficient.

Original languageEnglish
Pages (from-to)2055-2063
Number of pages9
JournalElectrochimica Acta
Volume47
Issue number13-14
DOIs
Publication statusPublished - May 25 2002

Keywords

  • Adsorption
  • Capacitance
  • Diffusion
  • Double layer
  • Gold

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

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