engleski

Impedance of Glassy Carbon/RuOx * nH2O/Nafion® Composite Electrodes

Development of various hydrous RuOx based composites which are effective as energy storage/conversion materials for super-capacitor electrodes has gained great interest, mainly owing to excellent capacitive properties of hydrous RuOx. However, because of the toxicity and high cost of ruthenium, there is a clear tendency to develop electrodes which would contain (very) small quantities of RuOx. Generally, hydrous RuOx stores energy by pseudo-capacitance which arises from fast and reversible red-ox transition of active ruthenium atoms and involves exchange of protons with electrolyte solution. Since the last process limits electrochemical utilization of ruthenium atoms to the surface regions, some efforts have already been made to disperse hydrous RuOx within the bulk of some porous 3-D material. Such material should allow better access for the electrolyte solution and serve as the binding agent at the same time. In this work, a number of differently prepared glassy carbon, GC/RuOx•nH2O/Nafion® composite electrodes with various amounts of hydrous RuOx and Nafion® are characterized in H2SO4 solution by electrochemical impedance spectroscopy (EIS). The final goal was to define optimal quantities of individual components for preparation of low impedance composite electrodes with high and immediately available specific capacities (almost capacitive impedance response). Composite electrodes were prepared on electrochemically activated glassy carbon electrode in three different routes: i) by coating the GC surface with suspension of RuO2 (Aldrich) and Nafion® in isopropyl alcohol, ii) by coating the GC surface with suspension of Nafion® in isopropyl alcohol, followed by electrochemical deposition and oxidation of Ru from RuCl3 solution and iii) by coating the GC surface with suspension of chemically oxidized ruthenium and Nafion® in isopropyl alcohol

RuO2; Nafion; Glassy carbon; electrochemical impedance spectroscopy

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