Highly dispersed ruthenium oxide nanoparticles on carboxylated carbon nanotubes for supercapacitor electrode materials

To enhance its pseudocapacitance, ruthenium oxide must be formed with a hydrated amorphous and porous structure and a small size, because this structure provides a large surface area and forms conduction paths for protons to easily access even the inner part of the RuO2. In this study, we report that highly dispersed RuO2 nanoparticles could be obtained on carboxylated carbon nanotubes. This could be achieved by preventing agglomeration among RuO2 nanoparticles by bond formation between the RuO2 and the surface carboxyl groups of the carbon nanotubes. Highly dispersed RuO2 nanoparticles on carbon nanotubes showed an increased capacitance, which can be explained by the fact that with the decrease in size protons were able to access the inner part of RuO2, so that its utilization was increased. The high dispersion of RuO2 is therefore a key factor to increase the capacitance of nanocomposite electrode materials for supercapacitors.