Mulder, Willem H.; Calvente, Juan J.; Andreu, Rafael
Author Affiliation, Ana.
Department of Chemistry
A kinetic model for the reductive desorption of self-assembled Thiol monolayers
Date of Publication
A kinetic model for the reductive desorption of self-assembled monolayers of short-chain alkanethiols has been developed. The monolayer is described as a set of close-packed thiol domains, which for mathematical convenience are modeled as circular and equal in size. Desorption is assumed to occur via two parallel paths, a first route involving the removal of the thiol molecules at the edge of the adsorbate domains, and a second route involving the desorption of the thiol molecules inside the patches through a nucleation and growth mechanism. Analytical expressions for the chronoamperometric current resulting from reductive desorption of the monolayer are also derived and compared with experimental results. Theorectical predictions were found to account satisfacorily for the dependence of the chronoamperometric shape with the desorption potential for butanethiol and nonanethiol monolayers. thus, the observed chronoamperometric broadening, and the simutaneous increase of the initial current, could be explained as a consequence of the greater importance of the edge desorption route when the overpotential is made more negative.....