MASS-TRANSPORT ACCOMPANIED WITH ELECTRON-TRANSFER BETWEEN THE GOLD ELECTRODE MODIFIED WITH 11-FERROCENYLUNDECANETHIOL MONOLAYER AND REDOX SPECIES IN SOLUTION - AN ELECTROCHEMICAL QUARTZ-CRYSTAL MICROBALANCE STUDY

An electrochemical quartz crystal microbalance (EQCM) was employed to investigate mass transport during the redox reaction of the ferrocenyl undecanethiolate (FcC(11)S(H)) monolayer modified gold electrode in so lution containing other redox species. The FcC(11)S monolayer on gold acts as a barrier for the electron transfer between a gold electrode a nd Fe(CN)(6)(4-/3-) in solution and as a mediator for the reduction of Fe3+ in solution. In both cases, electrochemical current responses we re complicated because the observed currents were due to the redox of both the ferrocenyl group immobilized on gold and others in electrolyt e solutions. The frequency change, i.e. interfacial mass change on the gold electrode surface, was observed only during the redox of ferroce nyl groups. The complex current response was deconvoluted into the cur rent components of redox reaction of ferrocene and that of other redox species in solution by comparing cyclic voltammograms with the curren t calculated from frequency changes. (C) 1997 Elsevier Science S.A.