STUDIES OF FERROCENE DERIVATIVE DIFFUSION AND HETEROGENEOUS KINETICS IN POLYMER ELECTROLYTE BY USING MICROELECTRODE VOLTAMMETRY

The heterogeneous electron transfer rate constants (k(s)) of seven fer rocene derivatives were estimated using cyclic voltammograms under mix ed spherical/semi-infinite linear diffusion and steady-state voltammet ry at a microdisk electrode in polymer electrolyte. The k(s) and diffu sion coefficient (D) are both 100 to 1000-fold smaller in polymer solv ent than in monomeric solvents, and the D and k(s) decrease with incre asing polymer chain length. The results conform to the difference of v iscosity (eta) or relaxation time (tau(L)) for these different solvent s. The k(s) and D increase with increasing temperature, and the activa tion barriers of the electrode reaction are obtained. The influences o f the substituting group in the ferrocene ring on k(s) and D are discu ssed. The k(s) are proportional to the D of the ferrocene derivatives, which indicates that solvent dynamics control the electrode reaction. (C) 1998 Elsevier Science S.A.