Hybrid material polypyrrole/[SiCr(H2O)W11O39]5-:: Electrogeneration, properties, and stability under cycling

Hybrid materials constituted by polypyrrole doped with the polyoxometalate (POM) anion [SiCr(H2O)W11O39](5-) were electrogenerated from acetonitrile solutions. The electrochemical behavior of the hybrid films was studied by cyclic voltammetry in three different electrolytes formed by two anions and two cations, dissolved in acetonitrile. Following both, the film weight evolution and the solutions composition with cycling, together with an EDX study of the film showing the electrochemical evolution, have allowed the identification of the ions interchanged during the redox processes for the different studied electrolytes. Prevalent cation interchange, continuous substitution of the POM anion by the anion in solution, and partial electrodissolution of the hybrid film were identified as prevalent processes in the different electrolytes. Conducting measurements show that the films present a high room temperature conductivity that is thermally activated. Magnetic measurements confirmed the presence of the paramagnetic POM in the films and indicate that the number of pyrrole monomers per cationic charge is about 4.5. These results have been confirmed by elemental analysis.