Electrochemical and AFM Study of the 2D-Assembly of Colloidal Gold Nanoparticles on Dithiol SAMs Tuned by Ionic Strength

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• 作者：Daniel Garc铆a Raya ; Christophe Silien ; Manuel Bl谩zquez ; Teresa Pineda ; Rafael Madue帽o
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：July 3, 2014
• 年：2014
• 卷：118
• 期：26
• 页码：14617-14628
• 全文大小：522K
• ISSN：1932-7455

文摘

Colloidal deposition of gold nanoparticles (AuNPs) on 1,8-octanedithiol self-assembled monolayer (ODT-SAM) Au(111) surfaces is accomplished by spontaneous adsorption from solutions with different ionic strengths under diffusion-controlled transport. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show that AuNPs|ODT-SAM|Au(111) ensembles efficiently promote electron transfer (ET) across an ODT insulating monolayer as a function of the surface coverage of the particles (胃), which is tuned by controlling both deposition time and ionic strength conditions. ET rate constants are obtained by fitting EIS data to a Randles circuit and thus, 胃 can be determined according to the partially blocked electrodes theory. Saturation particle densities (螕_max) and surface coverage (胃_max) values are in good agreement with those determined by atomic force microscopy (AFM) measurements indicating the validity of the electrochemical approach. 胃_max and adsorption kinetics of AuNPs assembly are interpreted in terms of a random sequential adsorption (RSA) model based on long-range repulsive electrostatic interactions between particles treated as soft-spheres. Consequently, physicochemical parameters of the colloidal nanoparticles are extracted.