Characterization of hydrous ruthenium oxide/carbon nanocomposite supercapacitors prepared by a colloidal method

Amorphous nanostructured composite materials with different RuO₂ loadings on carbon were prepared by colloidal method. The annealing temperature was found to be critical in optimizing the electrochemical performance of this material. FT Raman study confirmed that ruthenium complex converted to ruthenium oxide after annealing at 100°C. The specific capacitance of RuO₂/carbon composite electrode (40wt.% Ru) was calculated by using cyclic voltammetry, which was to be 407F/g. The specific capacitance of RuO₂·xH₂O was estimated to be approximately 863F/g by subtracting the contribution of double layer capacitance resulting from carbon in the composite. Transmission electron microscopy indicated that the particle size of RuO₂·xH₂O on carbon was approximately 3nm. By increasing the Ru loading over 60wt.%, the particle size of RuO₂ increased up to several micrometers resulting in a decrease of the utilization of RuO₂, the specific surface area and the rate capability.