Control of the electrochemical properties of fullerenes via the chemical modification approach has attracted considerable attention. However, surface modification of fullerene cages with various functional groups can lead to the destruction of their original structures. Herein, we report a simple approach for controlling the electrochemical properties of fullerene thin films formed on Au(111) electrodes in various ionic liquids (ILs). A total of eight reversible redox couples for six reductive and two oxidative processes were observed for fullerenes in ammonium- and pyrrolidinium-based ILs. The redox potentials, the differences between two successive redox potentials, the average values of these potential differences for fullerene reduction, and the electrochemical band gaps of fullerene films in various ILs were found to depend on the cation and its alkyl chain length, the anion, and the chemical structure of the fullerene. Highly charged C anions were reduced more easily than C anions. An increase in the alkyl chain length of the cation led to an increase in the average potential difference between two successive redox potentials for fullerene reduction. The results indicate that the electrochemical band gaps of fullerenes can be manipulated using ILs with appropriate anions, which can be determined based on the size of the anion and the charge distribution.

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Adsorption and electrochemical reaction of graphen oxide (GO) at an Au surface was studied by surface enhanced infrared absorption spectroscopy (SEIRAS). GO film on the Au electrode is formed within 1 min. in 0.4 mg ml −1 of GO aqueous dispersion solution. Also, it was shown that, by applying −1.0 V vs Ag/AgCl, the epoxy group of GO was reduced in 0.4 mg ml −1 of GO and 0.1 M NaClO4 solution, and the reaction was irreversible within the potential region under the experimental conditions studied here.