Green Synthesis Of Carbon Nanotube And Graphene Supported Ruthenium Dioxide Composite Materials And Their Electrochemical Performance For Supercapacitors

Through the use of simple, convenient and green preparation methods, namely self redox of the system and hydrogen peroxide oxidation, Ru O2/CNTs composite was prepared with high specific capacitance. The control variables for the preparation of Ru O2/CNTs composite, such as reaction time, reaction temperature and the loading amount of Ru O2, were investigated. The optimum variables were then obtained. The structure and performance of the prepared Ru O2/CNTs composites with the two methods were characterized and studied. The results show that the particle sizes prepared by both methods are very small and Ru O2 particles distribute evenly on the surface of carbon nanotubes. The overall capacitance performance of the Ru O2/CNTs composite prepared by self redox of the system is superior to that of the Ru O2/CNTs composite prepared by hydrogen peroxide oxidation. The specific capacitance value of the Ru O2/CNTs composite by self redox of the system is up to 261.5 F/g under the optimum preparation conditions.Graphene oxide(GO) was prepared by a modified Hummers method. Using the self-redox properties of GO and Ru Cl3, Ru O2/r-GO composites was synthesized by a facile, one-step and green oxidation-reduction method. The Ru O2 particle sizes of the as-prepared composites are even smaller and homogeneously distributed on the surface of r-GO. The results of electrochemical tests show that the Ru O2/r-GO composite obtains a specific capacitance value of 296F/g with the loading mass of 40wt%, reaction temperature of 100℃and current density of 1A/g. Under the current density of 5A/g, the capacitance retention of the composite stays 94.8% after 1000 circulation, showing a rather good electrochemical stability. At the same time, the Ru O2/r-GO composites synthesized by hydrogen peroxide oxidation were investigated, of which the capacitive performance is still inferior to that of the one by self redox of the system. The hydrogen peroxide plays a positive role at the early period of the reaction or at lower temperature. Self redox of the system has the advantages of simple, green and environmental friendliness, and at the same time, makes more uniform distribution of Ru O2 particles with the smaller particle size and better stability, thus being a better method for the preparation of both Ru O2/CNTs and Ru O2/r-GO composites. When compared Ru O2/CNTs with Ru O2/r-GO, Ru O2/r-GO shows superior capacitive performance than Ru O2/CNTs.