The information of carboxylated carbon nanotubes

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.To functionalize our carboxylated carbon nanotubes  (produced by the CVD method), we perform a reflux in concentrated sulfuric / nitric acid. This process results in a large concentration of carboxyl (-COOH) groups on the nanotube surface, and also generates other groups. After functionalization, these carboxylated nanotubes have 2-7 wt% COOH by titration. These typically have a high zeta potential, varying from -30 to -70mV as a function of pH. Suspensions made from these nanotubes can be very stable.

Images below are FTIR spectrum and Raman Spectrum Data of our COOH functionalized Multiwall nanotubes. Click on the images to view in PDF. More analytical data can be requested via email.
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