Voltammetric studies on microcrystalline C₆₀ adhered to an electrode surface by solvent casting and mechanical transfer methods

Abstract.

Voltammetric studies on C₆₀ fullerene particles adhered to an electrode surface by solvent casting or mechanical transfer exhibit evidence of nucleation and growth controlled processes for the C₆₀ ^0/– and C₆₀ ^–/2– solid state when the modified electrode is in contact with acetonitrile solutions containing NBu₄ ⁺ electrolyte. Although peak potentials and peak separations are dependent on scan rate as well as the amount of deposit and temperature, potentials obtained using a zero-current extrapolation method are almost independent of all these parameters. These data enable reversible potentials of –816 and –1168 mV vs. Ag/Ag⁺ to be obtained in acetonitrile (0.1 M NBu₄PF₆) respectively for the processes: ${\rm C}_{{\rm 60}} \left( {{\rm solid}} \right) + {\rm NBu}_{\rm 4}^ + \left( {{\rm solution}} \right) + {\rm e}^ - {\rm }\buildrel {} \over \rightleftharpoons {\rm NBu}_{\rm 4} {\rm C}_{{\rm 60}} {\rm (solid)}$ and ${\rm NBu}_{\rm 4} {\rm C}_{{\rm 60}} \left( {{\rm solid}} \right) + {\rm NBu}_{\rm 4}^{\rm + } \left( {{\rm solution}} \right){\rm + e}^{\rm - } \buildrel {} \over \rightleftharpoons \left( {{\rm NBu}_{\rm 4} } \right)_{\rm 2} {\rm C}_{{\rm 60}} \left( {{\rm solid}} \right)$ . Images obtained by scanning electron microscopy reveal that both the crystalline and particle size is enhanced by 60 s of reductive electrolysis, with the detected (NBu₄)₂C₆₀ crystals being slightly larger than those of (NBu₄)C₆₀. After a short period of potential cycling or controlled potential electrolysis, it is concluded that the data obtained by either method of surface adherence are almost indistinguishable, as are their morphologies.