The Effect of Adsorption of Ions of the Hexacyanoferrate(II)/(III) Redox Pair on Self-Assembly of Octanethiol at Its Adsorption from Aqueous Solutions on Gold Electrode

The effect of components of the redox pair K₃Fe(CN)₆]/K₄Fe(CN)₆] on the dynamics of formation of octanethiol (OT) monolayers from aqueous thiol-containing solutions of 0.1 М NaClO₄ is studied by cyclic voltammetry (CVA). The formation of OT monolayers is shown to depend on the presence of ions of hexacyanoferrate(II)/(III) in solution. Being added to solution, the components of the Fe(CN)₆]^3–/4– redox pair sharply increase the time of formation of the insulating monolayer OT films and make them less stable. The destabilizing and inhibiting action of Fe(CN)₆]^3–/4– ions becomes stronger as their concentration in solution increases. The adsorption activity of individual components of the redox pair is assessed. The strong and approximately equal adsorption activity of ions Fe(CN)₆]^3– and Fe(CN)₆]^4– on gold in the presence of octanethiol is observed. At the same time, OT and the hexacyanoferrate(II)/(III) ions can be placed in the following row: OT > Fe(CN)6]^3– ≈ Fe(CN)₆]^4–. Recommendations are given on how to eliminate the interfering action of the K₃Fe(CN)₆]/K₄Fe(CN)₆] redox-pair ions when studying the insulating properties of thiol monolayers on gold.