Nickel and cobalt oxides supported on activated carbon derived from willow catkin for efficient supercapacitor electrode

Abstract

Supercapacitors have attracted more interest due to the advantages of extended cycle life, great power density, and fast charging and discharging rate. A chemical activation technique involving KOH and carbonization at 600 °C in inert gas was used to successfully synthesize activated carbons (AC) derived from willow catkin (WC). Metal salts like cobalt nitrate and nickel sulfate are used as initial precursors to the synthesis of cobalt oxide nanoparticles and nickel oxide nanoparticles. The prepared cobalt oxide-activated carbon nanocomposites and nickel oxide-activated carbon nanocomposites are calcined at 300°С for 3 h. To improve the electrochemical performance, different weight percentages of nickel oxide and cobalt oxide nanoparticles (10, 25, 50, and 75 wt%) are prepared on cobalt oxide-activated carbon nanocomposites and nickel oxide-activated carbon nanocomposites, respectively. The elemental analysis, structural, and morphology properties of the prepared samples were carried out. The prepared nanocomposites are used as working electrodes for supercapacitors. The AC electrode has the lowest specific capacitance of 105 F. g−1. The 25NiO@Co3O4-AC and 25Co3O4@NiO-AC nanocomposite electrodes have the highest specific capacitances of 800.9 and 691.8 F. g−1 at a current density value of 1.0 A. g−1 and an energy density value of 136.6 and 116.2 Wh. Kg−1. This is due to the good dispersion of nickel oxide and cobalt oxide with the prepared AC.