A theory of electrode reactions through bridge transition states; bridges with a discrete electronic spectrum

Abstract

Summary A theory has been developed for outer-sphere non-adiabatic electron transfer reactions at electrodes, to or from which an electron is transferred via ionic or molecular bridge species adsorbed on the electrode surface. Assuming a discrete energy spectrum for the discharging species and for the bridge, and neglecting interaction between adsorbed bridges, current-voltage relationships have been calculated for all overvoltages, and it is shown that for suitable relative positions of the electronic terms, the rate of the bridge-assisted electron transfer is higher than that of the direct electron transfer. Experimental data for various systems have been considered, and a semiquantitative agreement with the theory is found for the reduction of [Fe(CN) 6 ] 3− .