Electron transfer across C16 hexadecanethiol/Au(111) to tethered Os(bpy)2(pyCH2NH2)Cl centers enhanced by Au nanoparticles

CALVO, ERNESTO J.; HERRERA, SANTIAGO E.; DAVIA, FEDERICO; WILLIAMS, FEDERICO J.

Bologna

Congreso; 69th annual meeting of the international society of electrochemistry; 2018

The gold nanoparticle mediated electron transfer was studied using electrochemical impedance spectroscopy on a full surface system architecture. A gold spherical microelectrode was modified with 16-amino-1-hexadecanethiol creating an insulator film and gold nanoparticles were electrostatically adsorbed on top of the self-assembled monolayer (SAM). Redox centers of an Os2+ complex were tethered to the surface using lipoic acid linker. A variation of the Creager-Wooster method was developed in order to get quantitative information regarding the electron transfer (ET) kinetics of the system. A model in which two or more ET processes with different time constants can be decoupled from a single measurement was used to fit the experimental data. Two parallel ET mechanisms were observed: one in which the electrons flow by tunneling between the surface and the redox couples with a low kET 0= 1.3 s-1, and a second one in which an enhancement of the electron transfer is produced due to the presence of the gold nanoparticles with a kET0 = 7 x 104 s-1. In this study we demonstrate that the enhancement of the gold nanoparticle mediated electron transfer is present only in a local environment and that the nanoscale architecture results crucial in order to maximize the enhancement effects.