Influence of Spatial Redox Distribution on the Electrochemical Behavior of Electroactive Self-Assembled Monolayers

Abstract

Packing restrictions and hydrophobic interactions are likely to lead to a spatial distribution of redox centers in electroactive monolayers. A mean field analysis of the electrochemical implications of spatial redox dispersion in SAMs, including the possibility of surface ion pair formation, has been carried out. The boundary value problem associated with a layered distribution of potential-induced charges has been solved by using the orthogonal collocation technique under equilibrium conditions. Spreading of the redox centers into a 3D dielectric slab results in broader and asymmetric voltammograms, reflecting a layer-by-layer redox conversion. It is also shown that the voltammetric shape is sensitive to the specific features of the spatial redox distribution, and theoretical requirements for the appearance of asymmetric broadening are examined in terms of the electrostatic properties of the monolayer. It is suggested that this type of spatial inhomogeneity may cause some of the broad and asymmetric volt...