Preparation and Characterization of Aligned Carbon Nanotube-Ruthenium Oxide Nanocomposites for Supercapacitors

A novel type of ruthenium oxide (RuO2)‐modified multi‐walled carbon nanotube (MWNT) nanocomposite electrode (RuO2/MWNT) for supercapacitors has been prepared. The nanocomposites were formed by depositing Ru by magnetic‐sputtering in an Ar/O2 atmosphere onto MWNTs, which were synthesized on Ta plates by chemical vapor deposition. Cyclic voltammetry, chronopotentiometry, and electrochemical impedance measurements were applied to investigate the performance of the RuO2/MWNT nanocomposite electrodes. The capacitance of the MWNT electrodes in 1.0 M H2SO4 is significantly increased from 0.35 to 16.94 mF cm−2 by modification with RuO2. The RuO2 film on the surface of the nanotubes is composed of small crystal grains with tilted bundle‐like microstructures, as observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results demonstrate a promising route to prepare RuO2/MWNT‐based double‐layer supercapacitors. Extra capacity: Modifying multi‐walled carbon nanotubes (MWNTs) by forming a composite with ruthenium oxide yields materials with high electronic capacitance (see SEM image). A near 50‐fold increase in capacitance, as compared to bare MWNTs is observed, which suggests such materials may find application as supercapacitors.