Super Capacitor Electrode With The Preparation Of New Hybrid Carbon Materials

In this paper, NiO/CNTs, NiO/graphene, and NiO/CNTs-graphene composite films were successfully fabricated on nickel foam by electrophoretic deposition (EPD).Carbon nanotubes (CNTs) were firstly carboxylated by ultrasonication in a mixture of concentrated acid and dispersed in ethanol. Then, with Ni(NO3)2addition, the charges on the CNTs surfaces reversed to positive due to the adsorption of Ni2+on CNTs. The Ni2+-decorated CNTs moved towards the cathode (nickel foam) by electric field force and simultaneously Ni2+ions bound on the CNTs were reduced to form a metal of Ni. After deposition, the metallic Ni on the as-formed CNTs films was oxidized to NiO in the drying process. Finally, NiO/CNTs composite film electrodes were successfully fabricated. A multiple-deposition scheme was employed in our experiments to investigate the relationship between the capacitance of the electrodes and the mass of the deposited Ni2+-coated CNTs. And the electrode made of2×NiO/CNTs films on nickel foam displayed the best capacitive behavior and delivered a specific capacitance of1075F g-1at the current density of5A g-1.Graphene oxide (GO) was dispersed in isopropyl alcohol (IPA). Then, with Ni(NO3)2addition, the charges on the GO surfaces reversed to positive due to the adsorption of Ni2+on GO. Finally, NiO/GO composite film electrodes were successfully fabricated by EPD. Surprisingly, we found that the color of the electrodes changed (from yellow to black) after cyclic voltammetry scan in KOH. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy revealed that GO was reduced to graphene and with the increase of NiO in NiO/GO films, the reductive degree of GO improves. In addition, the capacitive behavior of NiO/graphene composite film electrodes was improved with the increase of NiO and the specific capacitance could reach1240F g-1at the current density of5A g-1.Based on the reseach above, NiO/CNTs-graphene composite film electrodes were successfully fabricated by EPD. Various weight ratios of CNTs/GO and the content of NiO was investigated. It was found that the electrode with50%CNTs exhibited an optimal electrochemical capacitance. Besides, the capacitance of the composite electrodes was improved with the increase of NiO and the specific capacitance could reach1402F g-1at the current density of5A g-1.