Coalescence inhibition of hydrous RuO2 crystallites prepared by a hydrothermal method

Abstract

Coalescence of particulates accompanied with crystal growth upon annealing at/above 200 °C, found for hydrous Ru O2 (Ru O2 ·n H2 O) prepared by a sol-gel process, is effectively inhibited by the formation of Ru O2 ·n H2 O nanocrystallites in a hydrothermal process. This thermal stability, attributable to the barrier originated from the lattice energy of crystallites, maintains high water content, nanocrystalline structure, and porous nature of Ru O2 ·n H2 O annealed at elevated temperatures from 200 to 400 °C. A hydrothermal derived Ru O2 -based supercapacitor with high specific capacitance (ca. 200 F g-1 measured at 100 mA cm-2) and a cycle lifetime longer than 40 000 cycles, resulting from thermal stability, is demonstrated. © 2006 American Institute of Physics.