Paper Title
Hydrothermalsynthesis of Copper/Ruthenium Oxides and Multi-Walled Carbon Nanotube Nanocomposites for Supercapacitor Application

Abstract
As for the increasing demands of environmentally friendly and fast charge/discharge energy storage device, supercapacitor (SC) technologies have been attracting increasing research attention. Pseudo-capacitive and electronic double layer capacitors (EDLCs) are two major working mechanisms of supercapacitors. The first one, known as Faraday’s capacitance,which is based on pseudocapacitive materials, e.g. CuO, RuO2, MnO2, V2O5, RuO2, Co2O3, In2O3, NiO/Ni(OH)2 etc., and tends to be with higher energy density. The second one is based on charging separation at the electrochemical interface between electrode and electrolyte, which contributes higher power density and long cycle stability. Carbon nanotube (CNTs), graphene, carbon nanofibers, carbon spheres, carbon aerogel, carbon black and activated carbon are quality EDLC materials. All of them have already been well studied during the past decades. Furthermore, the hybrid of them gives the most possibility for high power and high energy densities. It aims of to build a supercapacitor with high specific capacitance, power density, energy density, and long cycle life. In this study, copper/ruthenium oxides (Cu/RuO2) and multi-walled carbon nanotubes (MWCNTs) were integrated to synthesizethe hybrid electrodes by hydrothermal process. The optimized ratio of CuO to RuO2 was obtained by adjusting the concentration of metal precursor. The electrochemical properties were investigated in a three-electrode configuration cell; the working electrodes were prepared by blade coating on stainless steel sheets, platinum wire as the counter electrode and Ag/AgCl electrode as the reference electrode with 3 M ((NH4)2SO4) electrolyte. As the result, the optimizedprocessing conditions were 12 hours hydrothermal under 180 oC, with Cu, Ru and C mass fraction of 7 %, 24 % and 60 %, respectively. The proposed CuO/RuO2/MWCNT composite electrode shows the specific capacitance of 462 F/g (measures under current density of 1 A/g). Keywords - Hybrid Capacitor, Copper Oxide, Ruthenium Oxide, Multi-Walled Carbon Nanotube, Hydrothermal Method, Specific Capacitance