Modification of a Au(111) Electrode with Ethanethiol. 1. Adlayer Structure and Electrochemistry

Abstract

We have used in-situ scanning tunneling microscopy and cyclic voltammetry to study self-assembled monolayers of ethanethiol on Au(111) electrodes. The adlayer was found to consist of domains of two different ordered structures, one corresponding to a (p × √3), well-established for other short-chain alkanethiols, and the other to an oblique primitive (4 × 3) superstructure, not previously reported for nonfunctionalized alkanethiols. At potentials slightly negative of 0 V vs SCE the adlayer undergoes a structural transformation that eventually leads to the formation of small pits and islands on the surface. Electrochemical studies in 0.1 M H2SO4 have revealed that around −0.31 V vs SCE the ethanethiol adlayer is reductively desorbed. Oxidative desorption of ethanethiol takes place at 1.15 V. The cathodic as well as the anodic desorption of the monolayer was monitored by scanning tunneling microscopy.

A facile method to prepare noble metal nanoparticles modified Self-Assembly (SAM) electrode

“…The electrochemical windows were chosen as 0.0 » +1.35 V and ¡0.50 » 0.0 V to study the electrooxidation and desorption of thiol on electrode surface, respectively. When the electrochemical window is 0.0 » +1.35 V, in the first cycle of CV curves, a sharp peak at around 1.1 V was observed in the positive-going scan as showed in Figure 2a, the oxidation peak corresponding to the oxidation of mercapto group (-SH), which is consistent with literature [24]; the relatively small peak at 1.3 V corresponding to the surface oxidation of bared Au, since most of the Au surface was cover by thiol, the oxidation peak of Au surface was smaller than that of thiol. On the second cycle of CV curves, the peak at 1.1 V was disappear while the peak at 1.3 V was largely increased, indicated than the adsorbed thiol was totally oxidized in the first cycle.…”

Label‐Free Impedance Biosensors: Opportunities and Challenges

“…finite R leak ) was noted even at 0 V bias vs. Ag/ AgCl with a C 16 SAM in the absence of a redox species [168]. This is likely due to voltageinduced structural rearrangement of the SAM that results in pinholes [169] or permeation of SAM with ions or water molecules [170]. Extreme DC bias voltages can actually oxidize or reduce the bonds between a metal electrode and biological probe layer (reported values for gold-thiol are summarized in [166]).…”

Current understanding of the structure, phase transitions and dynamics of self-assembled monolayers on two- and three-dimensional surfaces

“…The two kinetics steps in SAM formation and the presence of pin-hole defect free SAMs have been shown by CV studies [77]. Oxidative desorption of short-chain alkanethiols is observed at 1.15 V [78]. Mohtat et al used CV to study the behaviour of alkanethiols on Ag surfaces [79].…”