Physical and electrochemical characterization of hydrous ruthenium oxide/ordered mesoporous carbon composites as supercapacitor

Ruthenium oxide/ordered mesoporous carbon composites materials were prepared by impregnating an ordered mesoporous carbon CMK-3 with RuCl3 · xH2O solution followed by annealing in nitrogen atmosphere from 80 to 400 °C. The content of ruthenium oxide in the composites ranged from 10.0 to 30.7 wt.%. X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption measurement and transmission electron microscopy (TEM) were used to characterize the composites. The results showed that the ruthenium oxide deposited on CMK-3 mesoporous carbon was hydrous and amorphous when annealed up to 400 °C. The specific capacitance of the composites was determined by cyclic voltammetry. Such composites had high specific capacitance, which was derived from the high specific surface area of CMK-3 mesoporous carbon and the pseudo-capacitance of amorphous RuO2. In addition, the specific capacitance depended on the annealing temperature and the RuO2 content. As the temperature increased, the specific capacitance decreased. In contrast, the specific capacitance increased with higher RuO2 content and reached 633 F/g with a heavy content. However, as the RuO2 content increased, its contribution to the pseudo-capacitance became poorer. The rate capability of the composite electrodes also decreased as a function of RuO2 content, due to an increase in the equivalent series resistance (ESR) and the overall capacitance.