Potential-assisted deposition of alkanethiols on Au: Controlled preparation of single- and mixed-component SAMs

The commonly used method of preparing RS/Au self-assembled monolayers (SAMs) involves a passive incubation process in a nonabsorbing solvent. Preparation of mixed-component SAMs is particularly problematic under these conditions. The time course of the open circuit potential in the passive adsorption experiment suggests that control of the deposition potential could lead to a faster and ultimately more complete SAM formation process. This is shown to be the case, as both C-16 RS/Au SAMs and mixed C-16/HOOCC15S/Au SAMs are shown to be readily prepared in approximately 15 min from 5 mM thiol solutions at potentials ranging from 200 to 600 mV (vs Ag/AgCl). The blocking properties of the resulting C16 SAMs are excellent. This technique provides access to mixed-composition SAMs otherwise inaccessible using deposition under open circuit conditions.