Effect of rGO Coating on Interconnected CoO Nanosheets and Improved Supercapacitive Behavior of CoO/rGO/NF Architecture.

In this study, the effect of reduced graphene oxide (rGO) on interconnected CoO nanosheets and the improved supercapacitive behaviors is reported. By optimizing the experimental parameters, we achieved a specific capacitance of 1016.4 F g for the CoO/rGO/NF (nickel foam) system at a current density of 1 A g. However, the CoO/NF structure without rGO only delivers a specific capacitance of ~520.0 F g at the same current density. The stability test demonstrates that CoO/rGO/NF retains ~95.5% of the initial capacitance value even after 3000 charge-discharge cycles at a high current density of 7 A g. Further investigation reveals that capacitance improvement for the CoO/rGO/NF structure is mainly because of a higher specific surface area (87.8 m g) and a more optimal mesoporous size (4-15 nm) compared to the corresponding values of 67.1 m g and 6-25 nm, respectively, for the CoO/NF structure. rGO and the thinner CoO nanosheets benefit from the strain relaxation during the charge and discharge processes, improving the cycling stability of CoO/rGO/NF.