Spectroelectrochemical characterization of thin fullerene films in room temperature ionic liquids

Room-temperature ionic liquids were used as electrolytes for in situ studies of the transitions of solution cast fullerene films. 1-Butyl-3-methyl-imidazolium tetrafluoroborate (BMIMBF4), 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIMPF6) and 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BDiMIMBF4) were used in this study and the techniques used are cyclic voltammetry and in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Infrared spectra were recorded during the reversible redox processes of the C60 films showing a three-step one electron reduction and reoxidation reaction. After reoxidation some part of the C60 film remained in its C60- form. The IR bands obtained during electrochemical reduction of C60 in ionic liquids were compared with the spectra reported for C60 films upon reduction in the presence of different cations in organic solutions.