1. Abteilung Elektrochemie and Leitfähige Polymere, Leibniz-Institut für Festkörper- und Werkstofforschung, Helmholtzstrasse 20, D-01069 Dresden, Germany, and Faculty of Industrial Chemistry and Environmental Engineering, University “Politehnica” of Timisoara, Piata Victoriei 2, RO-300006 Timisoara, Romania