Microwave-assisted fabrication of high-performance supercapacitors based on electrodes composed of cobalt oxide decorated with reduced graphene oxide and carbon dots

This study presents microwave-assisted preparation of cobalt oxide (Co3O4) based nanocomposite electrodes doped with carbon dots and reduced graphene oxide. The calcination of the precursors at 400 ? for 2 h results in nanocomposites. A three-electrode cell in 2M KOH solution is used for the electrochemical measurements. The carbon dot containing electrodes enables the highest specific capacitance of 936 Fg(-1) at 0.5 Ag-1 current density. Specific capacitances of pure Co3O4, and Co3O4@RGO electrodes are 448 Fg(-1) and 482 Fg(-1) at 0.5 Ag-1, with good rate capability even at 10 Ag-1, respectively. The cyclic stability of the electrodes is reasonably high and the electrodes retain 93%, 87%, and 88% of their initial capacitance after 10,000 cycles for Co3O4, Co3O4@RGO, and Co3O4@RGO@CDs, respectively. The optimized Co3O4@RGO@CDs electrodes were used to fabricate a symmetric supercapacitor that exhibits high specific capacitance (126 Fg(-1) 0.25 Ag-1) and long cycle life (%81 retention after 10,000 cycles). The fabricated supercapacitor has energy density of 17.5 Wh kg(-1) and power density of 2522 W kg(-1). The outstanding results demonstrate the promise of carbon dots doped transition metal oxides-based nanoparticles as promising electrodes for supercapacitor applications.

Automated summary

This study presents the microwave-assisted preparation of cobalt oxide-based nanocomposite electrodes doped with carbon dots and reduced graphene oxide. The electrodes with carbon dots exhibit the highest specific capacitance and good rate capability, even at high current densities. The optimized electrodes are used to fabricate a symmetric supercapacitor with high specific capacitance and long cycle life.