Electrochemical Metal Deposition on Top of an Organic Monolayer

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• 作者：Deyu Qu ; Kohei Uosaki
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：September 7, 2006
• 年：2006
• 卷：110
• 期：35
• 页码：17570 - 17577
• 全文大小：128K
• 年卷期：v.110,no.35(September 7, 2006)
• ISSN：1520-5207

文摘

Electrochemical deposition of metals (platinum or gold) only on top of an organothiolate, 1,4-benzenedimethanethiol (BDMT) or hexanedithiol (HDT), self-assembled monolayer (SAM) on a Au(111) substratewas achieved by electrochemical reduction of PtCl₄^2- or AuCl₄^- ion, which was preadsorbed on one freethiol end group of the dithiol SAM formed on a Au surface, in a metal-ion-free sulfuric acid solution atpotentials more negative than the reduction potential of the metal ion. Angle-resolved X-ray photoelectronspectroscopy (AR-XPS) measurement after the reduction of preadsorbed PtCl₄^2- ion on BDMT/Au(111)electrode showed the presence of Pt not underneath but on top of the BDMT SAM. After a negative potentialscan of the Pt/BDMT/Au(111) electrode to -1.30 V in 0.1 M KOH solution, a typical cyclic voltammogramof a clean Au(111) electrode was obtained, showing that the BDMT SAM with a Pt layer was reductivelydesorbed. These results proved that a Pt-BDMT SAM-Au substrate sandwich structure without a shortcircuit between the two metals was successfully constructed by this technique. Furthermore, a decanethiol(DT) monolayer was constructed on a Au layer, which was formed by the reduction of preadsorbed AuCl₄^-ion on HDT/Au(111) electrode. The formation of DT/Au/HDT/Au(111) structure was confirmed as two cathodicpeaks corresponding to reductive desorption of DT from Au on top of the HDT/Au(111) at -0.97 V and thatof Au/ HDT from Au(111) at -1.12 V were observed when potential was scanned negatively to -1.35 V.