Hydrous ruthenium dioxide/multi-walled carbon-nanotube/titanium electrodes for supercapacitors

Composite electrodes prepared by vertically aligned multi-walled carbon nanotubes (MWCNTs) coated with hydrous ruthenium dioxide (RuO2·nH2O) have previously been used in various supercapacitors. The specific capacitance when using RuO2·nH2O/MWCNT/Ti as electrodes in 1.0 M H2SO4 aqueous solution can reach up to 1652 F/g at a scan rate of 10 mV/s, which is larger than that of RuO2·nH2O/Ti or MWCNT/Ti. In this study, a RuO2·nH2O/MWCNT/Ti composite electrode was examined by X-ray photoelectron spectroscopy, which revealed the existence of hydrous ruthenium dioxide in the Ti current collector. The capacitive behavior of the electrode was analyzed by cyclic voltammetry and the galvanostatic charge–discharge method, and the morphology of the composite electrode was examined by scanning electron microscopy.