Electrochemical nanostructuring of fullerene films—spectroscopic evidence for C₆₀ polymer formation and hydrogenation

Electrochemical reduction of ordered C₆₀ fullerene films in aqueous solution was studied by AFM, FTIR and Raman spectroscopy, mass spectrometry and elastic recoil detection analysis. During the irreversible reduction process the film morphology changed from a heteroepitaxial (111) surface to a nanostructured array with clusters of 20 to 50 nm lateral size on average. On the molecular level the initial C₆₀ underwent electrochemical reactions to form C₆₀ polymers and hydrogenated C₆₀. Chemical follow-up reactions of electrochemically formed C₆₀⁻ with water are responsible for the different reduction behaviour of C₆₀ films in aqueous solution compared to C₆₀ reduction in organic solvents and to C₆₀ doping with alkali metals. Based on the spectroscopic analysis a reaction scheme accounting for the chemical processes at the C₆₀ | aqueous electrolyte interface is presented.