Electrochemical Studies of C60/Pd Films Formed by the Reduction of C60 in the Presence of Palladium(II) Acetate Trimer. Effects of Varying C60/Pd(II) Ratios in the Precursor Solutions

Cyclic voltammetric studies of the electrochemical formation and redox properties of C60/Pd films are reported. Films used in this work are generated under multicyclic scans in an acetonitrile/toluene (1:4, v/v) mixture containing fullerene C60 and palladium(II) acetate trimer as the film precursors and tetra(n-butyl)ammonium perchlorate as supporting electrolyte. The structure and electrochemical properties of the deposited layers depend on the relative concentrations of the precursors (C60 and {Pd(OAc)2}3) present in the growth solution. In the presence of excess palladium(II) acetate trimer, palladium, as well as the redox active film, is deposited, as shown by electrochemical studies of the behavior of the modified electrodes toward hydrogen evolution and palladium oxidation in aqueous acidic solution. At very negative potentials, all of the films decompose which is presumed to be due to the repulsive interaction between negatively charged C60 centers and mechanical strain induced by the incorporation of cations from the supporting electrolyte in the film. However, the stability of the films depends on the C60 to Pd(II) ratio in the solution from which the film was prepared. The presence of deposits of palladium within the film changes the mechanical and electrochemical stability of the films and also alters the reversibility of the charging processes.