The use of radio frequency plasma discharges of neat vinylferrocene to chemically modify pyrolytic graphite electrode surfaces is discussed. The plasma process yields a stable coating of electroactive polymer, the thickness of which may be varied by controlling the duration of the plasma discharge reaction. X-ray photoelectron spectroscopy has been utilized to characterize the modified electrode surfaces, and the results indicate that the surface composition varies as a function of placement of the substrate in the plasma reactor. The electrochemical behavior of the plasma polymerized vinylferrocene films has been investigated by cyclic voltammetry. The voltammograms show marked differences in charge transport kinetics in aqueous vs. nonaqueous (acetonitrile) media. The plasma-deposited films are shown to be electrocatalytically active in the oxidation of ascorbic acid in aqueous acidic solutions. The implications of charge transport, counter ion transport, and substrate (ascorbic acid) transport kinetics with respect to the efficiency of the electrocatalytic reaction are also discussed.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the financial support of these studies by the Research Corporation (Grant No. 8640).