Study on the Electrochemical Behavior of Poly(ferrocenylsilane) Films

Abstract

The electrochemical behavior of polyferrocenyldimethylsilane (PFDMS) films and polyferrocenylmethylphenylsilane (PFMPS) films deposited on a glassy carbon electrode in 1.0 M aqueous LiClO4 was investigated by means of cyclic voltammetry (CV). The influences of supporting electrolyte concentration, temperature, film thickness, and the molecular structure of the polymer on the electrode process are discussed. In 1.0 M aqueous LiClO4, the electrochemical processes of two polymer films on glassy carbon electrodes were complex and have a low rate of electron transport and mass diffusion. At routine sweep rates, quasi-reversible or irreversible CV processes of the films were observed, but at slow sweep rates, nearly reversible CV waves were recorded. Below 0.05 M, the concentration of the supporting electrolyte had a considerable effect on the CV behavior of the film, especially on the oxidation wave, that is, the kinetics of film oxidation was limited by the counterion flow into the polymer phase. Elevated temperature increased the rate of the electrode process and improved the reversibility of the film electrode process. The diffusion rate of the active species in the film electrode process was reduced with the film thickness. Furthermore, the molecular structure of the polymer had a notable influence on the electrochemical behavior of the films. The phenyl groups in PFMPS hobbled the chain mobility in the polymer and restricted the surface charge transfer and the active species diffusion so that the kinetic parameters of the PFMPS films, especially the surface transfer coefficient αnα, were found to be smaller than those corresponding to the PFDMS films. The shapes of the CV peaks of the PFMPS films were broader, the peak potentials for both cathodic and anodic peaks were more positive, and the peak separation ΔEp was larger.