AN UNUSUAL ELECTRON-TRANSFER BEHAVIOR OF FERROCENE IN AQUEOUS MICROEMULSION SYSTEMS

The electrochemical behavior of ferrocene in an aqueous microemulsion (pentan-1-ol/sodium dodecyl sulfate (SDS)/aq. H2SO4) has been studied using an ultramicroelectrode. Contrary to the generally expected rever sible peak, the experiments show the presence of a second oxidation pe ak during the reverse scan at low scan rates where the peak correspond ing to ferricinium ion reduction is nearly absent along with the unant icipated appearance of a current dip. These observations are rationali zed using a novel type of coupling between heterogeneous (electrochemi cal) and homogeneous (chemical) electron transfer processes. The compo sition of the medium, especially the acid concentration, affects the e lectron transfer of the solubilized probe and there exists a threshold acid concentration for achieving maximum anodic peak current.