Adsorption Behavior of 11-Mercapto-1-undecanol on Au(111) Electrode in an Electrochemical System
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- 作者：Yaw-Chia Yang ; Teng-Yuan Chang ; Yuh-Lang Lee
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：March 15, 2007
- 年：2007
- 卷：111
- 期：10
- 页码：4014 - 4020
- 全文大小：1334K
- 年卷期：v.111,no.10(March 15, 2007)
- ISSN：1932-7455
文摘
In-situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV) were used to study the phaseevolution of 11-mercapto-1-undecanol (MUO) adlayer on an Au(111) electrode. The effect of variouselectrolytes, including HClO4 and H2SO4, on the adsorption behavior was studied. The MUO adsorption wasfound to initiate mainly at the intersectional corner of herringbone rows of an Au(111) reconstruction structurein both of the electrolytes. The following growth of an adsorbed cluster develops first along the face-centered-cubic (fcc) position of the herringbone structure. In the HClO4 solution, the MUO molecule is first adsorbedin a flat-lying orientation when the dose concentration of MUO is low, growing to an ordered domain ofstriped structure (
phase) with a molecular arrangement of (12 × 
3). When the surface coverage becomeshigh, the hydrocarbon chains of MUO lift off from the Au(111) plane, forming a more condensed and saturatedphase, the 
phase, identified as (3 × 3)R30
. At a high dose concentration of MUO, however, thestriped phase does not appear. Due to the fast adsorption of thiol groups at high dose concentrations, thehydrocarbon chains-gold interaction is inhibited, and therefore, a flat-lying orientation of MUO moleculescannot be obtained. In the H2SO4 solution, the striped phase does not form even at a low dose concentrationand, instead, the phase appears directly in the low-coverage stage. The distinct phenomena observed forthe two electrolytes are attributed to the different interactions of anionic ions with the gold surface. It hasbeen shown that sulfate ions adsorb more strongly than perchlorate ions on a gold surface. The stronglyadsorbed sulfate ions in the electrical double layer are supposed to resist the direct contact of hydrocarbonchain with the gold surface which also prevents the formation of a flat-lying orientation.
phase) with a molecular arrangement of (12 × 3). When the surface coverage becomeshigh, the hydrocarbon chains of MUO lift off from the Au(111) plane, forming a more condensed and saturatedphase, the phase, identified as (3 × 3)R30. At a high dose concentration of MUO, however, thestriped phase does not appear. Due to the fast adsorption of thiol groups at high dose concentrations, thehydrocarbon chains-gold interaction is inhibited, and therefore, a flat-lying orientation of MUO moleculescannot be obtained. In the H2SO4 solution, the striped phase does not form even at a low dose concentrationand, instead, the phase appears directly in the low-coverage stage. The distinct phenomena observed forthe two electrolytes are attributed to the different interactions of anionic ions with the gold surface. It hasbeen shown that sulfate ions adsorb more strongly than perchlorate ions on a gold surface. The stronglyadsorbed sulfate ions in the electrical double layer are supposed to resist the direct contact of hydrocarbonchain with the gold surface which also prevents the formation of a flat-lying orientation.