The electrochemical desorption of n-alkanethiol monolayers from polycrystalline Au and Ag electrodes

Widrig, Cindra A.; Chung, Chinkap; Porter, Marc D.

doi:10.1016/0022-0728(91)85271-p

Cited by 1,064 publications

(1,264 citation statements)

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“…Current integration, after correction of the double layer contribution, yields a desorption charge of approximately (160 AE 10) mC cm À2 . This value is considerably larger than 70 mC cm À2 typically reported for alkanethiols, 71 and indicates contributions of parallel processes such as bromide (perchlorate) desorption and cation (potassium) re-adsorption. The occurrence of the corresponding anodic peak P3 0 at E ¼ À0.950 V points to a partial oxidative re-adsorption of HS-6V6-H on Au (111) Au (111)-(1 Â 1) electrodes modified with the dithiol HS-6V6-SH, bromide salt, according to protocol 3 ( Fig.…”

Section: Stm and Sts Measurementsmentioning

confidence: 58%

Two-dimensional assembly and local redox-activity of molecular hybrid structures in an electrochemical environment

et al. 2006

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The self-assembly and redox-properties of two viologen derivatives, N-hexyl-N 0 -(6-thiohexyl)-4,4 0 -bipyridinium bromide (HS-6V6-H) and N,N 0 -bis(6-thiohexyl)-4,4 0 -bipyridinium bromide (HS-6V6-SH), immobilized on Au(111)-(1 Â 1) macro-electrodes were investigated by cyclic voltammetry, surface enhanced infrared spectroscopy (SEIRAS) and in situ scanning tunneling microscopy (STM). Depending on the assembly conditions one could distinguish three different types of adlayers for both viologens: a low coverage disordered and an ordered ''striped'' phase of flat oriented molecules as well as a high coverage monolayer composed of tilted viologen moieties. Both molecules, HS-6V6-H and HS-6V6-SH, were successfully immobilized on Au(poly) nano-electrodes, which gave a well-defined redox-response in the lower pA-current range. An in situ STM configuration was employed to explore electron transport properties of single molecule junctions Au(T)|HS-6V6-SH(HS-6V6-H)|Au(S). The observed sigmoidal potential dependence, measured at variable substrate potential E S and at constant bias voltage (E T À E S ), was attributed to electronic structure changes of the viologen moiety during the one-electron reduction/re-oxidation process V 21 2 V 1d . Tunneling experiments in asymmetric, STM-based junctions Au(T)-S-6V6-H|Au(S) revealed current (i T )-voltage (E T ) curves with a maximum located at the equilibrium potential of the redox-process V 21 2 V 1d . The experimental i T À E T characteristics of the HS-6V6-H-modified tunneling junction were tentatively attributed to a sequential two-step electron transfer mechanism.

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Section: Stm and Sts Measurementsmentioning

confidence: 58%

Two-dimensional assembly and local redox-activity of molecular hybrid structures in an electrochemical environment

et al. 2006

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“…Electrochemical techniques have been previously reported to clean Au chip surfaces of contaminants effectively enough for alkanethiol attachment and subsequent SAM formation. 18,[31][32][33][34][35] Application of sufficiently oxidative (+0.85 V vs. SCE in 0.1 M H 2 SO 4 ) or reductive (21.03 V vs. SCE in 0.1 M NaOH) potentials on gold induces desorption of surface species, including the alkylthiolates used to make specific monolayers. 36 This technique has the additional positive attribute for our studies in that it permits Au pads at the tips of our cantilevers to be cleaned individually or as a group.…”

Section: Introductionmentioning

confidence: 99%

Formation and removal of alkylthiolate self-assembled monolayers on gold in aqueous solutions

Canaria

Maloney

et al. 2006

Lab Chip

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We report the development of novel reagents and approaches for generating recyclable biosensors. The use of aqueous media for the formation of protein binding alkylthiolate monolayers on Au surfaces results in accelerated alkylthiolate monolayer formation and improvement in monolayer integrity as visualized by fluorescence microscopy and CV techniques. We have also developed an electrocleaning protocol that is compatible with microfluidics devices, and this technique serves as an on-chip method for cleaning Au substrates both before and after monolayer formation. The techniques for the formation and dissociation of biotinylated SAMs from aqueous solvents reported here may be applied towards the development of Au-based sensor devices and microfluidics chips in the future. A potential use of these devices includes the specific capture and triggered release of target cells, proteins, or small molecules from liquid samples.

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“…After Widrig et al reported that alkanethiolates are desorbed from the gold 3 surface by the following one-electron reduction process in an alkaline aqueous solution [17]:…”

Section: Introductionmentioning

confidence: 99%

“…Au -SR + e -=> Au + RS - (1) many electrochemical studies of the reaction (1) have been carried out because the peak area and the shape of the cathodic peak for the reductive desorption and its peak potential provide useful information of the SAM such as the adsorbed amount, stability, adsorption energy, orientation, and substrate morphology [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. For example, it was found that the longer the alkylchain, the more negative the reductive peak potential, reflecting the stronger van der Waals attractive interaction among alkylchains [17].…”

Section: Introductionmentioning

confidence: 99%

“…For example, it was found that the longer the alkylchain, the more negative the reductive peak potential, reflecting the stronger van der Waals attractive interaction among alkylchains [17]. The reductive desorption process has been investigated by many techniques including electrochemistry [17][18][19][20][21][22][23][24][25][26], FT-IR [27][28][29], electrochemical QCM [30][31][32], and in situ STM [33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer of decanethiol on the Au(111) surface in KOH+ethanol solution

Sumi

Wano

Uosaki

2003

Journal of Electroanalytical Chemistry

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The electrochemical characteristics of an Au(111) electrode were investigated in 0.1 M KOH ethanol solutions containing various concentrations of decanethiol. Anodic and cathodic peaks corresponding to the oxidative adsorption and reductive desorption, respectively, of a self-assembled monolayer (SAM) of decanethiol were observed. Both peaks negatively shifted with the increase in the thiol concentration by ca. 57 mV/decade, showing that the redox process is a one-electron process. The adsorbed amount determined from the charge corresponding to the reductive desorption increased with an increase in the decanethiol concentration but never reached the saturated amount as long as the cyclic voltammograms were continuously recorded with the sweep rate of 10 -200 mV s-1. It increased with the holding time at +0.1 V, which was much more positive than the anodic peak potential, and reached the saturated amount in ca. 10 min in the 10 μM thiol solution. The reductive peak potential also negatively shifted with the holding time but for a longer period. It kept shifting for ca. 60 min in the 10 μM thiol solution, which is much longer than the time when the adsorbed amount reached the saturated value. These results suggest that the formation of a highly ordered SAM requires a much longer time than the adsorption of the thiol.2

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The electrochemical desorption of n-alkanethiol monolayers from polycrystalline Au and Ag electrodes

Cited by 1,064 publications

References 42 publications

Two-dimensional assembly and local redox-activity of molecular hybrid structures in an electrochemical environment

Two-dimensional assembly and local redox-activity of molecular hybrid structures in an electrochemical environment

Formation and removal of alkylthiolate self-assembled monolayers on gold in aqueous solutions

Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer of decanethiol on the Au(111) surface in KOH+ethanol solution

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