CHRONOAMPEROMETRIC STUDY OF THE REDUCTION OF CHEMISORBED THIOLS ON AU(111)

We report chronoamperometric measurements of the reduction of a monola yer of butanethiols chemisorbed on an Au(lll) single crystal electrode in 0.1M KOH. The reductive desorption of the butanethiol monolayer is found to follow a nucleation and growth mechanism. The mechanism of t he reductive removal of the butanethiols changes smoothly from a progr essive to an instantaneous nucleation and growth mechanism as the pote ntial is stepped to more negative values. For the most negative applie d potentials the reductive current decays at a slower rate than predic ted from the model. We suggest that this is caused by the fact that th e reduction process becomes limited by the diffusion of the thiols fro m the surface. (C) 1997 Elsevier Science S.A.