Voltammetric study of fullerene C60 and fullerene C60 nanotubes with sandwich method

Two sandwich-type electrodes (RTIL/C60/SWNT/GCE and RTIL/C60 nanotube/SWNT/GCE) with fullerene C60 or fullerene C60 nanotubes interlayer covered by room temperature ionic liquid (RTIL) membrane on single-walled carbon nanotubes (SWNTs) modified glassy carbon electrode (GCE) surface were fabricated. Cyclic voltammetry and differential pulse voltammetry were used to characterize their electrochemical behaviors and the difference between fullerene C60 and fullerene C60 nanotubes was investigated and the reason was presumed for the first time. It has been observed that 4 pairs of quasi-reversible redox peaks occurred at the RTIL/C60/SWNT/GCE, while only two peaks at the RTIL/C60 nanotube/SWNT/GCE. The cathodic and anodic peak potentials did not shift with the change of pH, indicating that no protons were involved in the electrode reaction processes. So the redox reaction of the fullerene C60 or fullerene C60 nanotubes could be considered as a multi-step one-electron transfer process and fullerene C60 behaved like an electron accumulator to accept and release electrons. While, the reductive products of fullerene C60 nanotubes could not be oxidized again in the reverse scan and the electrode process was irreversible. The fullerene C60 monomer released the accumulated electrons more easily than the fullerene C60 nanotubes. The electrochemical behaviors showed that the electrochemical processes at both electrodes were adsorption-controlled processes.