Soft template synthesis of mesoporous Co3O4/RuO2•xH2O composites for electrochemical capacitors

Co3O4/RuO2 center dot xH(2)O composites with various Ru content (molar content of Ru=5%, 10%, 20%, 50%) were synthesized by one-step co-precipitation method. The precursors were prepared via adjusting pH of the mixed aqueous solutions of Co(NO3)(2)center dot 6H(2)O and RuCl3 center dot 0.5H(2)O by using Pluronic123 as a soft template. For the composite with molar ratio of Co:Ru=1:1 annealed at 200 degrees C, Brunauer-Emmet-Teller(BET) results indicated that the composite showed mesoporous structure, and the specific surface area of the composite was as high as 107 m(2)g(-1). The electrochemical performances of these composites were measured in 1 M KOH electrolyte. Compared with the composite prepared without template, the composite with P123 exhibited a higher specific capacitance. When the molar content of Ru was rising, the specific capacitance of the composites increased significantly. It was also observed that the crystalline structures as well as the electrochemical activities were strongly dependent on the annealing temperature. A capacitance of 642 F/g was obtained for the composite (Co:Ru = 1: 1) annealed at 150 degrees C. Meanwhile, the composites also exhibited good cycle stability. Besides, the morphologies and textural characteristic of the samples were also investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM). (C) 2007 Elsevier Ltd. All rights reserved.