Preparation and electrochemical capacitance of ruthenium oxide-titania nanotube composite

摘要

A well-aligned titania nanotube array grown on titanium sheet was fabricated by an anodization process in hydrofluoric acid-phosphoric acid-ethylene glycol aqueous electrolyte. Electroactive ruthenium oxide was filled into independent titania nanotubes or deposited on the surface of planar titanium sheet by an electrodeposition-oxidation process. Electrochemical capacitances of these well-designed ruthenium oxides were investigated for supercapacitor applications. Accordingly, ruthenium oxide-titania/titanium (RuO_2-TiO_2/Ti) nanocomposite exhibits a much higher specific capacitance, power and energy density than ruthenium oxide/titanium (RuO_2/Ti) in sulphate acid electrolyte. The utilization efficiency of RuO_2 is intensively improved by introducing a novel electrode substrate with a nanotube array structure. Such a superior performance of RuO_2-TiO_2/Ti nanocomposite is ascribed to its highly accessible reaction sites of well-tailored RuO_2 on TiO_2 nanotubes.