Ion transport and ferrocene incorporation in electroactive fullerene films

Thick (10 mu m) C-60 films are prepared by sublimation at 575 degrees C for 5 min on a pyrolytic carbon film electrode. Scanning electron microscopy shows that the fullerene film consists of crystallites of random size and orientation. Raman spectroscopy shows peaks characteristic of C-60 films at 273, 495, 773, 1463, and 1571 cm(-1). The electrochemistry of these thick films is consistent with a reduction mechanism that is dominated by ion transport. In the proposed mechanism, swelling of the film and direct intercalation of cations compete as modes of ion transport. During swelling, ferrocene (Fc) diffuses into the C-60 film and can be trapped after film reoxidation. When Fc is present, a greater percentage of the film is reduced. The stability of the film with respect to successive redox cycles is also increased.