IN-SITU TWIN-ELECTRODE SPECTROCYCLIC VOLTAMMETRY WITH A CELL COMPOSEDOF A PAIR OF NAFION(R)-COATED INDIUM TIN OXIDE ELECTRODES EACH INCORPORATING RU(BPY)3(2+) AND METHYLVIOLOGEN

Electrochemical redox reactions in a twin-electrode (TE) type cell com posed of a couple of Nafion(R)-coated indium tin oxide (ITO) electrode s each incorporating Ru(bpy)3(2+) and methylviologen (MV2+) were analy zed by in-situ spectrocyclic voltammetry. The cell system, ITO/Nafion( R)[Ru(bpy)3(2+)]/aqueous electrolyte/Nafion[MV2+]/ITO, showed changes in visible absorption spectra induced by cyclic scanning of the potent ial difference between the two ITO electrodes. The spectral changes we re attributed to the redox reactions of Ru(bpy)3(3+/2+) and MV2+/+. sh owing a multicolor electrochromism. The potential difference (+ 1.73 V ) of the major redox wave in the cyclic voltammogram (CV) of the TE ce ll were close to the values (+ 1.76 V) calculated from the redox poten tials of each species. Small peaks in the TE-CV suggested side reactio ns with H2O and 02, as well as migrations of the redox compounds into the opposite membranes. When each redox membrane was precycled repeate dly in an aqueous electrolyte solution, before fabricating a TE cell, the cell showed very stable behavior after repeated cyclic scanning. I t has been shown that the present in-situ TE spectrocyclic voltammetry is useful for studying reactions occurring in practical devices.