One-step hydrothermal fabrication of strongly coupled Co3O4 nanosheets-reduced graphene oxide for electrochemical capacitors

In the work, we developed a one-step synthetic strategy to prepare a strongly coupled Co3O4 nanosheets-reduced graphene oxide (Co3O4 NSs-rGO) hybrid, and further utilized it as a promising electroactive material for electrochemical capacitors (ECs). During the hydrothermal procedure, the GO was reduced and Co3O4 NSs were in situ grown on the rGO sheets simultaneously due to the electrostatic interaction between the Co2+ and GO sheets. Electrochemical characteristics indicated that the Co3O4 NSs-rGO hybrid with similar to 7.2 wt% Co3O4 loading delivered a specific capacitance (SC) of 187 F g(-1) at 1.2 A g(-1). Furthermore, the SC degradation of the hybrid was similar to 6 and 9% at constant current densities of 1.2 and 5 A g(-1) after 1000 continuous charge-discharge cycles, demonstrating its desirable electrochemical stability. The synergetic effect of nanoscale size and good redox activity of the Co3O4 NSs combined with the high electronic conductivity of the rGO resulted in the enhanced electrochemical utilization at high rates. In addition, an activated carbon/Co3O4 NSs-rGO asymmetric EC was further fabricated, and exhibited a specific energy density of similar to 13.4 W h kg(-1), specific power density of similar to 2166 W kg(-1) and striking electrochemical stability with similar to 11% SC degradation after 1000 cycles.