Anodic Desorption Monitored by Voltammetric and Gravimetric Measurements for Fast Estimation of Surface Coverage of Complex Organic Molecules on Au Electrodes

A methodology for fast determination of surface coverage of molecules or nanostructures assembled in monolayers at the surface of gold electrodes has been developed. The approach is based on anodic oxidative desorption of the molecules which is controlled by synchronized electrochemical gravimetric and voltammetric measurements. Successive anodic scans induce degradation and oxidative desorption of the assembled molecules resulting in a decrease in electrode mass. The completion of desorption is accurately controlled by the charge associated with adsorption of hydroxyl and oxygen species at the bare gold surface. The proposed method can be used to (i) complement the classical approaches or (ii) to estimate the surface coverage for nanostructures whose adsorption requirements, such as long-time assembling, ex-situ chemical treatment and other ex-situ or in-situ multistage procedures, complicate utilization of common approaches. Adsorbed nanostructures composed of poly(amido) amine dendrimers terminated with thiol functionalized viologen head groups were used as the model objects to evaluate the proposed methodology.