Ru oxide/carbon nanotube composites for supercapacitors prepared by spontaneous reduction of Ru(VI) and Ru(VII)

A novel method based on spontaneous reduction of Ru(VI) and Ru(VII) is reported for the deposition of Ru oxide on multi-walled carbon nanotubes (MWCNT). Both purified and acid functionalized nanotubes (p-MWCNT and a-MWCNT) have been used to produce composite materials for use in high power aqueous supercapacitors. Specific capacitances of 213 +/- 16 Fg(-1) and 184 +/- 11 Fg(-1) were obtained for Ru oxide/p-MWCNT and Ru oxide/a-MWCNT composites, respectively. Specific capacitances for the Ru oxide component were 704 +/- 62 Fg(-1) and 803 +/- 72Fg(-1), respectively. Current vs. potential curves exhibited capacitance peaks at ca. +0.5V vs. Ag/AgCl. The Ru oxide/p-MWCNT composite was shown to be stable over 20,000 charge/discharge cycles. An advantage of the method is that no pre-treatment of the MWCNT is required for optimum performance. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.