Enhanced Capacitance of Porous Carbon Electrodes through Deposition of Small Amounts of NiO

Amorphous carbon and NiO/carbon composites were used as an electrode material for supercapacitors. The investigations were performed to evaluate the influence of the Ar/$C_2H_2$ ratio on the capacitance values of carbon and NiO/carbon electrodes. The surface morphology of the carbon electrodes changes from snowflake-like to columnar with the increase of the Ar/$C_2H_2$ ratio. The Raman scattering spectroscopy results demonstrated that the $I_{D}//I_{G}$ ratio decreases from 1.33 to 0.91 with the increase of the Ar/$C_2H_2$ ratio. It indicates the decrease of the sp^2 bonded carbon in the coatings. The specific capacitance of the carbon electrodes increases with the increase of the Ar/$C_2H_2$ ratio. The NiO/carbon electrodes show capacitance values 10 times larger as those of carbon electrodes. The largest specific capacitance of 27.7 F/g was obtained for NiO/carbon electrode, when carbon coating was deposited under Ar/$C_2H_2$=27.