Oxidative synthesis of RuOx•nH2O with ideal capacitive characteristics for supercapacitors

A simple method with a high product yield (about 99%), i.e., chemical oxidation of RUCl3-xH(2)O with H2O2, is Successfully developed for the synthesis of hydrous ruthenium oxide (denoted as RuOx.nH(2)O). The main product of this chemical synthesis is RUO2.nH(2)O with a significant amount of RuO3 from the X-ray photoelectron spectroscopy results. All RuOx.nH(2)O powders without and with annealing in air between 150 and 400degreesC for 2 h show an amorphous structure from the X-ray diffraction and electron diffraction analysis. The annealed RuOx.nH(2)O with the amorphous structure exhibits the ideal capacitive performance (i.e., highly electrochemical reversibility, high-power property, and excellent stability). ne specific capacitance of annealed RuOx.nH(2)O, measured at 25 mV/s from a RuOx.nH(2)O-coated graphite electrode (denoted as RuOx/G), is greater than or equal to500 F/g when the annealing temperature is between 200 and 350degreesC. (C) 2004 The Electrochemical Society.