Hydrothermal self-assembly and supercapacitive behaviors of Co(II) ion-modified graphene aerogels in H2SO4 electrolyte

•3D Co(II) ions modified graphene aerogels were prepared by one-step hydrothermal process.•The aerogel electrodes showed hybrid supercapacitor behaviors.•The aerogel electrodes exhibited high rate capability and long-term cycling stability.

Reduced graphene oxide (r-GO) aerogels decorated with divalent cobalt ions were synthesized via a one-pot hydrothermal self-assembly route. The interaction of Co(II) ions with 3D r-GO aerogels was investigated by spectroscopic techniques, including Raman, attenuated total reflectance infrared, and X-ray photoelectron spectroscopies. The excellent electrochemical properties of the aerogels were confirmed by cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy in an acid electrolyte (1 M H2SO4). The Co(II) ion-modified r-GO aerogels can be used as high-performance hybrid supercapacitor materials with a specific capacitance of 387.2 F g–1 at 1 A g–1 current density and a good cycling stability without capacity decay over 1000 cycles. The mechanical integrity enhancement of the hybrid r-GO aerogel framework and the improvement in its unique capacitive performance are attributed to the efficient interconnection produced by electro-active Co(II) ions.

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