Investigation of the structure of self-assembled monolayers of asymmetrical disulfides on Au(111) electrodes by electrochemical desorption

Azehara, Hiroaki; Yoshimoto, Soichiro; Hokari, Hirofumi; Akiba, Uichi; Taniguchi, Ikuo; Fujihira, Masamichi

doi:10.1016/s0022-0728(99)00160-6

Cited by 27 publications

(24 citation statements)

References 66 publications

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“… Their study revealed that the cleavage of the S–S bond occurs on the surface of the gold and that the films exhibit phase separation upon annealing for 8 h at 100 °C. Separately, Fujihira and co-workers examined the reductive desorption of mixed-chain disulfides (i.e., structure 8 in Figure ) on Au(111) electrodes using cyclic voltammetry (CV) . These authors found that a high concentration (i.e., ranging from 10 to 100 μM) of the disulfide in solution produced a relatively homogeneous film, but if the adsorption temperature was too high (i.e., 60 °C maximum) or was elevated for too long, phase separation occurred (i.e., separation was visible at 1, 10, and 22 h).…”

Section: Pursuit Of Uniquely Blended Interfacesmentioning

confidence: 99%

Homogeneously Mixed Monolayers: Emergence of Compositionally Conflicted Interfaces

et al. 2017

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The ability to manipulate interfaces at the nanoscale via a variety of thin-film technologies offers a plethora of avenues for advancing surface applications. These include surfaces with remarkable antibiofouling properties as well as those with tunable physical and electronic properties. Molecular self-assembly is one notably attractive method used to decorate and modify surfaces. Of particular interest to surface scientists has been the thiolate-gold system, which serves as a reliable method for generating model thin-film monolayers that transform the interfacial properties of gold surfaces. Despite widespread interest, efforts to tune the interfacial properties using mixed adsorbate systems have frequently led to phase-separated domains of molecules on the surface with random sizes and shapes depending on the structure and chemical composition of the adsorbates. This feature article highlights newly emerging methods for generating mixed thin-film interfaces, not only to enhance the aforementioned properties of organic thin films, but also to give rise to interfacial compositions never before observed in nature. An example would be the development of monolayers formed from bidentate adsorbates and other unique headgroup architectures that provide the surface bonding stability necessary to allow the assembly of interfaces that expose mixtures of chains that are fundamentally different in character (i.e., either phase-incompatible or structurally dissimilar), producing compositionally "conflicted" interfaces. By also exploring the prior efforts to produce such homogeneously blended interfaces, this feature article seeks to convey the relationships between the methods of film formation and the overall properties of the resulting interfaces.

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Section: Pursuit Of Uniquely Blended Interfacesmentioning

confidence: 99%

Homogeneously Mixed Monolayers: Emergence of Compositionally Conflicted Interfaces

et al. 2017

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“…29,30 Since Widrig et al reported that an alkanethiol SAM is desorbed from the gold surface by a one-electron reduction process in an alkaline aqueous solution, 31 many electrochemical studies on this reaction have been carried out. [32][33][34][35][36][37][38][39][40][41][42] The area, shape, and position of the cathodic peak for the reductive desorption provide useful information on the SAM such as the adsorbed amount, stability, adsorption energy, orientation, and substrate morphology. For example, it was found that the longer the alkyl chain is, the more negative the reductive peak is, reflecting stronger van der Waals attractive interaction among alkyl chains.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Oxidative Formation and Reductive Desorption of a Self-Assembled Monolayer of Decanethiol on a Au(111) Surface in KOH Ethanol Solution

Sumi

Uosaki

2004

J. Phys. Chem. B

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Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer (SAM) of decanethiol on a Au(111) single crystal electrode were examined in 0.1 M KOH ethanol solution containing various concentrations of decanethiol ranging from 1 µM to 1 mM. Anodic and cathodic current peaks corresponding to the adsorption and desorption of decanethiol, respectively, were observed in cyclic voltammograms of a Au(111) single crystal electrode obtained in 0.1 M KOH ethanol solution containing more than 10 µM of decanethiol. Positions of both peaks depended on the concentration of decanethiol, and they shifted negatively by ca. 0.057 V/decade with increase in decanethiol concentration. This result confirms that the adsorption and desorption of decanethiol is a one-electron process. The reductive charge, which consists of desorption charge and capacitive charge, increased when the sweep rate was decreased and the decanethiol concentration was increased and reached the saturated value of 103 ((5%) µC cm , which corresponds to the reductive charge of thiol SAM of full coverage with a ( 3 × 3)R30°structure. Potentiostatic SAM formation was also investigated by holding the potential at +0.1 V. The reductive charge, i.e., the coverage of the SAM, increased with time and reached the saturated value of 103 ((5%) µC cm -2 , corresponding to full coverage, after holding the potential at +0.1 V for a certain period of time. The time when the amount of adsorbed thiolate reached full coverage depended on the concentration of decanethiol. The higher the concentration was, the faster full coverage was reached. The desorption peak shifted negatively as the holding time at +0.1 V was increased even after the adsorbed amount had reached full coverage. These results suggest that the ordering of decanethiol SAMs requires a much longer time than the time required for full coverage adsorption. The position of the reductive desorption peak was independent of the thiol concentration if the electrode was kept at +0.1 V for long enough so that a highly ordered SAM was formed. The cathodic peak shifted negatively as the sweep rate was increased, showing that reductive desorption of the SAM was rather slow. The rate constant for the reductive desorption was determined from the potential dependent peak shift to be 0.24 s -1 , which is in good agreement with the value obtained for a SAM prepared without potential control, indicating that the quality of the electrochemically prepared SAM is as good as that of the SAM prepared nonelectrochemically.

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“…In theory, hydroxylamine can also be reduced, but the product of this electrochemical reduction reaction is usually ammonia [25], and hence there is no evidence that hydroxylamine, if formed, is also being reduced electrochemically at the potentials applied. In contrast, it is known that alkyl disulfides can be reduced in the range of -0.8 V to -1.0 V on gold electrode [26], and hence the presence of significant levels of these species could explain the coulometry results.…”

Section: Resultsmentioning

confidence: 99%

Reexamination of the Direct Electrochemical Reduction of S‐Nitrosothiols

Peng

Meyerhoff

2013

Electroanalysis

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We report here on the electrochemical reduction of S-nitrosothiol species (RSNO). Nitric oxide (NO) is the reported common product from electrochemically reduced RSNOs at physiological pH. However, studies here at pH 7.4 show that during the reduction of RSNOs (-0.6 V to -0.9 V, vs. Ag/AgCl), no significant amount of NO is detected. Gas analysis suggests RSNO are reduced to nitrous oxide (N2O) at pH 7.4 and can only be converted back to NO at more oxidizing voltages. Interestingly, at pH 4.0, a direct one-electron reduction of RSNOs appears to occur and generates significant amounts of NO from RSNO species.

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Investigation of the structure of self-assembled monolayers of asymmetrical disulfides on Au(111) electrodes by electrochemical desorption

Cited by 27 publications

References 66 publications

Homogeneously Mixed Monolayers: Emergence of Compositionally Conflicted Interfaces

Homogeneously Mixed Monolayers: Emergence of Compositionally Conflicted Interfaces

Electrochemical Oxidative Formation and Reductive Desorption of a Self-Assembled Monolayer of Decanethiol on a Au(111) Surface in KOH Ethanol Solution

Reexamination of the Direct Electrochemical Reduction of S‐Nitrosothiols

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