Ion Transport and Ferrocene Incorporation in Electroactive Fullerene Films

Abstract

Thick (10 μm) C60 films are prepared by sublimation at 575 °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 C60 films at 273, 495, 773, 1464, 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 C60 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.

Unusual electrocatalytic behavior of ferrocene bound fullerene cluster films

“…Once the C 60 in the cluster film undergoes reduction (reaction 1), the anion gets stabilized in the cluster film. As discussed in an earlier work, 25 the complexation between the C 60 anion and tetrabutylammonium cation (TBA 1 ) is responsible for the stabilization of reduced species in the cluster film. Szucs et al 30,31 have demonstrated that the cation stabilized reduced films of C 60 remain stable even when exposed to air.…”

“…Several studies in the past have reported the redox behavior of fullerene films cast on electrode surfaces. 1,16,24,25,29,38 The redox activity of these films depends upon the method of deposition and the medium in which the C 60 film is exposed. For example, the first and second electron reduction waves of C 60 films are merged to yield a broad reduction wave.…”

“…For example, the first and second electron reduction waves of C 60 films are merged to yield a broad reduction wave. 25 It was also pointed out that the swelling of the C 60 film plays an important role in controlling the redox activity of the film. The swelling of the film allows penetration of cations and redox active species such as ferrocene from solution.…”

“…The variation in the film morphology also affects the rate of ion transport within the C 60 film. 25 Recently, we have demonstrated the feasibility of forming spherical assemblies of C 60 and electron donors (ferrocene, amines, phenothiazine) as optically transparent clusters in mixed solvents. 26 The microheterogeneous environment of fullerene clusters facilitates trapping of electron donor molecules from solution.…”

Evidence for Nucleation-Growth, Redistribution, and Dissolution Mechanisms during the Course of Redox Cycling Experiments on the C60/NBu4C60 Solid-State Redox System: Voltammetric, SEM, and in Situ AFM Studies

“…The electrochemical redox-cycling of solid C 60 has been reported under a wide range of experimental conditions which include various deposition procedures such as solvent casting, − gas phase, and electrochemical deposition, and a range of contacting solvent systems and electrolyte salts. The interaction of the solid with neutral solution species , and also catalytic processes have been noted. Most extensive work has been published on the redox-cycling of solid C 60 deposited on an electrode and immersed in an acetonitrile solution containing NBu 4 + cations.…”