CHRONOAMPEROMETRIC STUDY OF THE REDUCTIVE DESORPTION OF ALKANETHIOL SELF-ASSEMBLED MONOLAYERS

Chronoamperometry has been used to study the reduction of aliphatic th iols chemisorbed on a Au(111) single crystal electrode in 0.1 M KOH. T he chronoamperograms of the reductive removal of butanethiol and nonan ethiol monolayers are relatively symmetric when the value of the final potential is not too negative. For more negative final potentials and for a hexadecanethiol monolayer, the chronoamperograms are asymmetric with a fast rising edge and a slow decay. We analyzed the chronoamper ometric data with a nucleation and growth model in which the reductive removal of a thiol monolayer starts by the creation of etching center s and continues with the reduction of the thiols that are at the edge of the etching centers. For the least negative final potentials, the s hort chain thiols (butanethiol and nonanethiol) are found to desorb re ductively from a limited number of etching centers. However, for the m ore negative final potentials and for the hexadecanethiol monolayer, t he reductive removal occurs homogeneously across the electrode surface instead of only at a few etching centers. (C) 1998 Elsevier Science S .A.