Iodide adsorption at Au(111) electrode in non-aqueous electrolyte: AC-voltammetry and EIS studies


Shatla A. S., Abd-El-Latif A. A., Ayata S., Demir D., Baltruschat H.

ELECTROCHIMICA ACTA, vol.334, 2020 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 334
  • Publication Date: 2020
  • Doi Number: 10.1016/j.electacta.2019.135556
  • Journal Name: ELECTROCHIMICA ACTA
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chimica, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Keywords: adsorption, Iodide ion, Single-crystal gold electrode, Propylene carbonate, Impedance, SCANNING-TUNNELING-MICROSCOPY, SINGLE-CRYSTAL-SURFACES, OXYGEN REDUCTION, IONIC LIQUIDS, HYDROGEN ADSORPTION, GOLD ELECTRODE, DOUBLE-LAYER, IMPEDANCE, PT(111), BROMIDE
  • Dokuz Eylül University Affiliated: Yes

Abstract

The adsorption/desorption of iodide ions on the Au (111) single crystal plane in propylene carbonate has been investigated by cyclic voltammetry, AC-voltammetry, and electrochemical impedance spectroscopy for various electrolyte compositions. In non-aqueous electrolyte (propylene carbonate), two broad reversible peaks are present in the cyclic voltammetry due to the adsorption/desorption of iodide at the electrode surface; they are broader than in the corresponding aqueous electrolyte. AC voltammetry shows sharp peaks of the iodide adsorption/desorption process at the same potential. Similar to the aqueous solution, the adsorption charge is in the range of 80 mu C cm(-2) and thus corresponds to a complete monolayer. The rate of iodide adsorption increases with iodide concentration in the solution as expected for a simple charge transfer. When hexafluorophosphate (PF6-) is the anion in the supporting electrolyte, the rate is also larger than when it is perchlorate (ClO4-). When the cation is changed, the rate also decreases (the adsorption resistance increases) by more than an order of magnitude in the sequence K+ > Na+ > Li+ > TBA(+) and, thus, in the same sequence as the radii of the solvated ions. (C) 2020 Elsevier Ltd. All rights reserved.