Preparation and characterization of RuO₂/polyaniline composite electrodes

Abstract

RuO₂–polyaniline (PANI) composites have been prepared by a novel method resulting in a composite material at the electrode surface. The method is based on the utilization of the chemical oxidation of aniline by the RuO₂ attached to the gold substrate in acid media. Electrochemical quartz crystal nanobalance combined with cyclic voltammetric and chronoamperometric measurements was used to study the oxidative deposition process as well as the exchange of ions and solvent molecules during cycling. The chemical reaction between RuO₂ and aniline results in a surface mass increase at the open circuit, and it also manifests itself in the substantial decrease of the open-circuit potential after addition of aniline into the supporting electrolyte. The potential range, the nature of the electrolyte, and the pH have been varied. The results of the piezoelectric nanogravimetric studies obtained for the redox transformation of RuO₂ and the composites are elucidated by the transport of ions and water molecules. It has been shown that the behavior of RuO₂ as well as of the composites strongly depends on the spontaneous and potential-dependent solvent sorption, the nature of the electrolyte, and the potential range. It has been found that the value of the specific capacitance was substantially increased by the polyaniline present without any significant deterioration of stability of the capacitor.