Recent advances in the electrochemistry of fullerene/transition metal co-polymers
AuthorWinkler, Krzysztof; de Bettencourt-Dias, Ana; Balch, Alan L.; Kutner, Wlodzimierz; Noworyta, Krzysztof
A review, with 20 refs. on formation and properties of the thin C60/transition metal layers is presented. These films can be prepd. by electroredn. from soln. contg. the fullerene and different metal precursors. So far, films contg. Pt, Pd, Rh, Ir, and Au atoms or ions were obtained. These layers exhibit redox cond. The electrochem. switching between the doped (conducting) and undoped (nonconducting) states involves both electron and ion transport within the film. The overall control of charge percolation through the copolymer is governed by the transport of supporting electrolyte cations. The structure and compn. of the layer depend on the relative concn. of the polymer precursors present in the grown soln. In the case of C60/Pd films, layers grown in solns. contg. an excess of the Pd complex consist of (-C60-Pd-)n polymeric chains sepd. by metallic Pd clusters. These layers are relatively flat and uniform. In the polymeric chains, the electrons are transferred through the chain by hopping between neighboring C60 units. The conduction bands in the Pd clusters make an exchange of electrons between sepd. (-C60-Pd-)n chains possible. Films formed in solns. with high concn. of Pd(II) complex are less uniform, rough, and porous. Metallic clusters dispersed in the polymeric layer also influence the charge transfer in redox systems at the film/electrolyte interface. The layer formed in soln. with relatively low concn. of Pd(II) complex inhibits the process of charge transfer at the polymer/electrolyte interface. On the other hand the layer contg. dispersed metal particles acts as a semi-metallic phase and does not influence the heterogeneous electron exchange. The reduced polymeric layers also exhibit the ability to exchange counterions between the solid and liq. phase and the layers can be doped with the redox active ions.