Preparation and characterization of electro-spun RuO₂-Ag ₂O composite nanowires for electrochemical capacitors

We synthesized RuO₂-Ag₂O composite nanowires by means of an electrospinning method and investigated the capacitance, high-rate performance, and cycle number dependence of the composite nanowire electrodes. In order to synthesize optimum RuO₂-Ag₂O composite nanowires, the relative mole ratio of Ag precursor to Ru precursor varied from ∼0.1 to ∼0.3. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy results show that crystalline RuO₂-Ag₂O composite nanowires (∼40-70 nm in diameter) are formed upon calcinations. Cyclic voltammetry results show that among the samples, the RuO ₂-Ag₂O composite nanowires fabricated with the mole ratio of ∼0.2 give the highest capacitance, excellent high-rate performance, and excellent retention of capacity (∼97%).