Raya, DG,Silien, C,Blazquez, M,Pineda, T,Madueno, R

2014

July

Journal Of Physical Chemistry C

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

Published

()

SELF-ASSEMBLED MONOLAYER RANDOM SEQUENTIAL ADSORPTION MEDIATED ELECTRON-TRANSFER ATOMIC-FORCE MICROSCOPY CHARGED LATEX-PARTICLES OMEGA-HYDROXY THIOL METAL NANOPARTICLES SURFACE-CHARGE IMPEDANCE SPECTROSCOPY DIFFUSIONAL DEPOSITION

118

14617

14628

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 vertical bar ODT-SAM vertical bar Au(111) ensembles efficiently promote electron transfer (ET) across an ODT insulating monolayer as a function of the surface coverage of the particles (theta), 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, theta can be determined according to the partially blocked electrodes theory. Saturation particle densities (Gamma(max)) and surface coverage (theta(max)) values are in good agreement with those determined by atomic force microscopy (AFM) measurements indicating the validity of the electrochemical approach. theta(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.

10.1021/jp502692q