Thermal-induced growth of RuO2 nanorods from a binary Ru-Ti oxide composite and alteration in supercapacitive characteristics

The growth of crystalline RuO2 nanorods has been thermally induced from a binary Ru-Ti oxide prepared by oxidative precipitation in an aqueous solution consisting of RuCl3 center dot xH(2)O, TiCl3 and H2O2. X-ray diffraction results show the formation of RuO2 nanocrystals as the annealing temperature is above/equal to 250 degrees C. The examination of surface morphology by transmission electron microscopic analysis confirms that the growth of RuO2 nanorods takes place in the high annealing temperature region. X-ray absorption spectroscopy (XAS) demonstrates that a minor amount of Ti atoms have been incorporated into crystalline RuO2, which partially occupy Ru sites in the octahedral RuO6 structure. The electrochemical results show that the binary Ru-Ti oxide annealed at 200 degrees C exhibits a much higher specific capacitance (ca. 2.5-fold improvement) and better capacitance retention in comparison with RuO2. Introducing Ti into RuO2 not only facilitates RuO2 utilization, but also enhances capacitance retention for the high-rate charge-discharge process. A schematic model is proposed to describe the growth mechanism of RuO2 nanorods from the binary Ru-Ti oxide and the function of Ti atoms within such composites for promoting the capacitive characteristics.