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Abstract: Hydrothermal treatment (HTT) of RuO2–Ta2O5/Ti electrode, as a method for improving their performance, for use in supercapacitors was investigated. The results show that HTT significantly enhances the stability of the electrodes. The specific capacitance of electrodes, subject to HTT in the temperature range 180–250°C remains unchanged after 1000 CV cycles between −0.2 and 1.1V vs. SCE; without HTT a decay to 97% of the initial is observed. The results also show that HTT decreases the activity of the electrodes for O2 and H2 evolution and increases the voltage window by 56–135mV for supercapacitors, but with a specific capacitance decrease of 7–27%. XPS analyses show the existence of more hydroxides after the HTT, which leads to a little increase in the interplanar distance as indicated in the XDR results. Contact angle measurements show the presence of a more hydrophilic surface after HTT. [Copyright &y& Elsevier]

Abstract: The preparation of RuO2–Ta2O5/Ti electrodes, by dip-coating, for use in supercapacitors was investigated. The stability and specific capacitance of the electrodes annealed at various temperatures was examined. The results show that highly stable electrodes with a specific capacitance of 170FgRuO2 −1 were obtained at approximately 250°C, while electrodes with a lower capacitance (130FgRuO2 −1) were obtained at 300°C. The annealing time needed to obtain a stable RuO2–Ta2O5/Ti electrode at various temperatures correlates well with the Arrhenius’ law: with the activation energy (E) of the annealing reactions for the electrodes being estimated as 73.5kJmol−1. SEM images of the electrodes show the coating films to have rough surface morphology with cracks 2–6μm in width. XRD data indicate that the coating films obtained are composed of crystalline RuO2 and amorphous tantalum oxide. [ABSTRACT FROM AUTHOR]