Desorption of Spontaneously Adsorbed and Electrochemically Readsorbed 2-Mercaptoethanesulfonate on Au(111)

Abstract

The desorption of 2-mercaptoethanesulfonate (MES) spontaneously adsorbed on Au(111) has been studied by using both potential-step and voltammetric experiments. From the amount of gold oxide formed during the oxidation sweep in the fingerprint region it is shown that the adsorption process induces structural changes of the gold surface. It is also shown that together with the reductive desorption of MES ions a concomitant faradaic process occurs. The results suggest that this process is connected to the reduction of solvent on the structurally modified gold electrode. The reductive desorption process of MES undergone at more negative potentials is characterized by a single peak in the voltammetric response and the presence of a maximum in the chronoamperogram. It is shown that the logarithm of the maximum current, the time at which the maximum current appears, and the peak width at half height depend linearly on potential. An experimental protocol for the desorption/readsorption of MES based on a potential-step experiment followed by cyclic voltammetry is outlined as an appropriate tool to analyze simultaneously the desorption of adsorbed and readsorbed MES. A linear dependence between the two desorption peak potentials and the surface concentration of adsorbate was observed. Changes in the environment surrounding the adsorbed moities and in the potential of zero charge of the electrode are shown to be the factors ruling this dependence.

Mercury Detection in Seawater Using a Mercaptoacetic Acid Modified Gold Microwire Electrode

“…The charge corresponding to the desorption peak in Figure 1 was Q ¼ 0.32 mC and taking into account a geometric surface area of A ¼ 0.0078 cm 2 the coverage of the electrode surface was G ¼ 4.23 Â 10 À10 mol cm À2 for a fresh prepared electrode which is similar to the results of other authors for other mercapto compounds [13,16,23]: e.g. the surface coverage found previously for MAA on gold was 6.9 Â 10 À10 mol cm…”

“…[13] and 3.8 Â 10 À10 mol cm À2 [23]. The charge evaluated from the peak of the dashed line in Figure 1 was Q ¼ 0.241 mC and corresponded to a surface coverage of G ¼ 3.19 Â 10 À10 mol cm À2 according to Equation 2, which showed a loss of 25% MAA during the electrochemical measurements.…”

Modification of nanoelectrode ensembles by thiols and disulfides to prevent non specific adsorption of proteins

“…This is useful, on one side, for protecting the Au nanoelectrode from undesired adsorption of proteins so avoiding interferences in the transduction of electrochemical signal. Note that, de-protection of the Au nanoelectrodes surface by electrochemical desorption of SAMs is, in principle, possible by performing the cathodic stripping of the SAM [47,48]. On the other hand, the present results open the way to the selective functionalization of NEEs, which can be performed by arranging different chemical functionalities on the gold of the nanoelectrodes vs. the organic surface of the polycarbonate.…”

A Novel Voltammetric Method for the Direct Determination of Copper in Complex Environmental Samples

“…In addition, it was possible that the SAM was desorption at a more negative potential. 19,23,24 A suitable deposition potential (0 V) was selected to ensure that the goldthiol bond was not destroyed during the process of SASV, so that the structure of the disorganized monolayer would not be destroyed. This was associated with the UPD of Cu 2+ .…”