Abstract
Thermally stable and porous RuO 2 ·xH 2 O with superior rate-retention capability is prepared by the H 2 O 2 -oxidative precipitation method modified with the cetyltrimethylammonium bromide (CTAB) template. The specific capacitance and rate-retention of RuO 2 ·xH 2 O are considerably enhanced by the CTAB modification and annealing at 200 °C because of extremely localized crystallization and pore opening of slightly sintered RuO 2 ·xH 2 O nanoparticles trapped with CTAB. This unique structure, confirmed by the X-ray absorption spectroscopic (XAS), Raman spectroscopic, and transmission electron microscopic (TEM) analyses, favors the utilization of RuO 2 ·xH 2 O nanocrystals and increases the electrolyte accessibility in comparing with RuO 2 ·xH 2 O without CTAB modification. The preferential orientation growth along the {101} facet of RuO 2 nanocrystals in some local regions is acquired by the CTAB modification and annealing in air at temperatures ≥350°C. Such preferential orientation growth of RuO 2 crystallites is attributable to the oxidation of trapped surfactants during the thermal annealing process, which adsorb on the high surface energy planes of RuO 2 . © 2014 Elsevier Ltd. All rights reserved.