Polymer films on electrodes: Part XVIII. Determination of heterogeneous electron transfer kinetics at poly(vinylferrocene) and nafion/Ru(bpy) 2+3 polymer-modified electrodes by convolution voltammetry

Abstract

Convolution voltammetry was used to evaluate the rates of heterogeneous charge transfer to ferrocene groups in poly(vinylferrocene) and to Ru(bpy) 2+ 3 in Nafion-modified electrodes under semi-infinite conditions. This technique allows correction for uncompensated resistance and double layer capacitance, as well as detrmination of the diffusion coefficient, D, transfer coefficient, α, and half-wave potential, E 1/2, from a single cyclic voltammogram. Vinylferrocene in solution and a bound copolymer of vinylferrocene and styrene in a ratio of 58:42 were also examined. For the polymer films, the heterogeneous charge transfer rate constants, k°, are 10 −4 ≥ k° ≥ 10 −5 cm/s; these values are about two order of magnitude smaller than those for the similar species in homogeneous solution. The values of k°/ D 1/2, however, are comparable to those in soluton; 10 > ( k°/ D 1/2) > 0.1 s −1/2.