Annealing effects on the physicochemical characteristics of hydrous ruthenium and ruthenium-iridium oxides for electrochemical supercapacitors

The electrochemical (EC) properties and stability of hydrous ruthenium oxide (denoted as RuO(x)(.)nH(2)O) and ruthenium-iridium oxide (denoted as (Ru + Ir)O(y)(.)mH(2)O) were systematically investigated in 0.5 M H2SO4 by cyclic voltammetry (CV) and chronopotentiometry (CP). The EC characteristics of RuO(x)(.)nH(2)O and (Ru + Ir)O(y)(.)mH(2)O annealed at temperatures equal to/above 200 degreesC were demonstrated to be more applicable for the EC supercapacitors. The crystalline information of these oxides annealed in air for 2 h up to 300 C was obtained from the X-ray diffraction (XRD) spectra. The morphologies of these oxide-coated electrodes were examined by a scanning electron microscope (SEM). The effect of annealing temperatures on the surface composition of (Ru + Ir)O(y)(.)mHO was studied by X-ray photoelectron spectroscopy (XPS). (C) 2002 Elsevier Science B.V. All rights reserved.