Investigation of redox reaction of Ru on carbon nanotubes by pulse potential electrochemical deposition

An approach based on pulse potential electrochemical deposition is demonstrated to be an attractive technique to improve the electrochemical performance of supercapacitors. Ruthenium oxide was electrochemically prepared onto an aligned carbon nanotube (CNT) film substrate by the control of on/off-time values of pulse potential method. A very thin and uniform coverage of amorphous RuO2–H2O nanoparticle layer on CNT was obtained. The pulse potential cycle was found to control the nucleation and growth of crystalline Ru and RuO2 particles. The high rate capacitive performance was achieved by the redox reaction of amorphous hydrous ruthenium oxide instead of crystalline RuO2. Preparing the electrode using 2 s on-time/5 s off-time at a controlled pulse voltage of 1 eV for 450 cycles results in a high capacitive performance of 1240 mF/g at a scan rate 50 mV/s.