CHARACTERIZATION OF MERCAPTOBENZIMIDAZOLE ADSORPTION ON AN Au(111) ELECTRODE

Document Type: Regular Paper

Authors

1 Electrochemistry Laboratory Research, Department of Physical Chemistry, Faculty of Chemistry, Tabriz University, I. R. of Iran,

2 Department of Materials Science, Faculty of Engineering, Tarbiat Modarres University, Tehran, I. R. of Iran

3 Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, England

Abstract

The adsorption of 2-mercaptobenzimidazole (2-MBI) on Au(111) has been studied with
cyclic voltammetry (CV), in-situ subtractively normalised interfacial FT-IR spectroscopy (SNIFTIRS)
and scanning tunnelling microscopy (STM). Although adsorbed 2-MBI reduces the interfacial capacity
and quenches the characteristic features of the cyclic voltammogram for sulfate adsorption,
heterogeneous electron transfer to both the [Fe(CN)6]4-/3- and [Ru(NH3)6]3+/2+ redox systems is only
partially impeded. Cyclic voltammetry has also been used to examine the reductive desorption of the
thiolate in KOH electrolytes and its subsequent re-adsorption. From the reductive desorption charge,
coverage of 2-MBI of 2.6 x 10-10 molecule cm-2 is estimated and this points to a flat-lying configuration
of the monolayer, in agreement with a previous XPS study. The SNIFTIRS and electrochemical results
show that adsorbed 2-MBI is displaced from the surface at positive potentials. STM imaging of adsorbed
2-MBI is also consistent with flat-lying molecules aligned in parallel rows.

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