The influence of electroactive solutes on the properties of electrochemically formed fullerene C60-based films

A study of simple redox solutes, ferrocene, N,N,N′,N′-tetramethyl-1,4-phenylenediamine, decamethylferrocene, bis(i-propylcyclopentadienyl)iron(II), [Ru(phen)3](ClO4)2, [Fe(bpy)3](ClO4)2, [Co(bpy)3](ClO4)2, and iodine has been performed at electrodes modified with polymeric fullerene films. Fullerene-modified electrodes were prepared by electropolymerization of C60 initiated by a trace amount of dioxygen or by simultaneous electroreduction of fullerene and a palladium(II) acetate trimer. These two films affect the electrochemical behavior of reversible redox systems differently. For the film formed from C60 and O2, a significant decrease of electrochemical activity is observed upon repeated potential cycling. The electrochemical activity of the film is stabilized by the redox solute added to the growth solution due to the catalytic oxidation of the fullerene film by the oxidized form of the redox system. Positively charged species can also be incorporated into the structure of the film during the electropolymerization process. The electrochemical behavior of redox-active solutes themselves becomes less reversible as the Pd/C60 film growth proceeds. This film incorporates also ferricinium ion, N,N,N′,N′-tetramethyl-1,4-phenylenediamine cation, decamethylferricinium ion, and to a smaller degree [Co(bpy)3]n+.