Preparation and characterization of composite electrodes of coconut-shell-based activated carbon and hydrous ruthenium oxide for supercapacitors

Abstract

The relationship between the structure-specific capacitance (F g^-1) of a composite electrode consisting of activated coconut-shell carbon and hydrous ruthenium oxide (RuO_x(OH)_y) has been evaluated by impregnating various amounts of RuOx(OH)y into activated carbon that is specially prepared with optimum pore-size distribution. The composite electrode shows an enhanced specific capacitance of 250 F g^-1 in 1 M H₂SO₄ with 9 wt.% ruthenium incorporated. Chemical and structural characterization of the composites reveals a homogeneous distribution of amorphous RuO_x(OH)_y throughout the porous network of the activated carbon. Electrochemical characterization indicates an almost linear dependence of capacitance on the amount of ruthenium owing to its pseudocapacitive nature.