Electrochemical evidence of the adsorption of alkanethiols on two sites on Ag(111)
被引:49
作者:
Mohtat, N
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h-index: 0
机构:
Univ Ottawa, Dept Chem, Ottawa, ON K1N 6N5, CanadaUniv Ottawa, Dept Chem, Ottawa, ON K1N 6N5, Canada
Mohtat, N
[1
]
Byloos, M
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h-index: 0
机构:
Univ Ottawa, Dept Chem, Ottawa, ON K1N 6N5, CanadaUniv Ottawa, Dept Chem, Ottawa, ON K1N 6N5, Canada
Byloos, M
[1
]
Soucy, M
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h-index: 0
机构:
Univ Ottawa, Dept Chem, Ottawa, ON K1N 6N5, CanadaUniv Ottawa, Dept Chem, Ottawa, ON K1N 6N5, Canada
Soucy, M
[1
]
Morin, S
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h-index: 0
机构:
Univ Ottawa, Dept Chem, Ottawa, ON K1N 6N5, CanadaUniv Ottawa, Dept Chem, Ottawa, ON K1N 6N5, Canada
Morin, S
[1
]
Morin, M
论文数: 0引用数: 0
h-index: 0
机构:
Univ Ottawa, Dept Chem, Ottawa, ON K1N 6N5, CanadaUniv Ottawa, Dept Chem, Ottawa, ON K1N 6N5, Canada
Morin, M
[1
]
机构:
[1] Univ Ottawa, Dept Chem, Ottawa, ON K1N 6N5, Canada
来源:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
|
2000年
/
484卷
/
02期
基金:
加拿大自然科学与工程研究理事会;
关键词:
thiols;
Ag(111) single crystal;
reduction;
chronoamperometry;
cyclic voltammetry;
FTIR spectroscopy;
D O I:
10.1016/S0022-0728(00)00063-2
中图分类号:
O65 [分析化学];
学科分类号:
070302 ;
081704 ;
摘要:
We present spectroscopic and electrochemical results consistent with the adsorption of alkanethiols on two sites and the formation of a very densely packed, stable, monolayer on Ag(111). A surface coverage of alkanethiols of 8.5 (+/- 0.4) x 10(-10) mol cm(-2) was calculated from the charge associated with the reduction of a monolayer of alkanethiols. Alkanethiol modified Ag(111) cm electrodes were found to have lower capacitances than the alkanethiol modified Au(111) electrodes. The lower capacitances are due to the higher surface concentration of alkanethiols on Ag(111). The very low intensity of the methylene CH stretching bands of alkanethiols with alkane chains of four to nine carbons chemisorbed on Ag(111) suggests a vertical orientation of all-trans alkane chains. No vibrational evidence of oxidation of the chemisorbed alkanethiols was found after exposure to air for up to 6 weeks. A fine structure consisting of two current peaks was observed in all cyclic voltammograms of the reduction of chemisorbed alkanethiols. This revealed that the reduction of chemisorbed alkanethiols occurs in two steps on Ag(111). Chronoamperometric measurements also support a two-step reductive desorption of alkanethiols. The high surface concentration of alkanethiols and the orientation of the alkane chains suggest that the fine structure in the voltammograms is due to the reduction of the alkanethiols from two adsorption sites. (C) 2000 Elsevier Science S.A. All rights reserved.