Hydrous ruthenium oxide prepared by steam-assisted thermolysis: Capacitance and stability

• RuO2·xH2O electrodes were directly prepared by thermolysis in heated steam.
• The RuO2·xH2O showed low crystallite and good hydrophilic.
• A good balance of electron/proton conductivity of the RuO2·xH2O was achieved.
• The RuO2·xH2O exhibited higher specific capacitance than that prepared in air.
• The RuO2·xH2O exhibited ultra-stable cycling ability.

Hydrous ruthenium oxides (RuO2·xH2O) with ultra-stable cycling ability were directly prepared on tantalum substrate by thermolysis of RuCl3 in heated steam environment. Characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and wettability test, the RuO2·xH2O showed lower crystallite and better hydrophilic than that are prepared by thermolysis in air. Their specific capacitance is twice as great as the latter. Moreover, this capacitance maintains nearly 100% after 100,000 cycles and its coulombic efficiency is 100% due to its good balance of electron/proton conductivity.