Reduced graphene oxide anchored Cu(OH)₂ as a high performance electrochemical supercapacitor

Developing new materials for electrochemical supercapacitors with higher energy density has recently gained tremendous impetus in the context of effective utilization of renewable energy. Herein, we report a simple one-pot synthesis of bundled nanorods of Cu(OH)₂ embedded in a matrix of reduced graphene oxide (Cu(OH)₂@RGO) under mild hydrothermal conditions of 80°C for 1 h. The synthesized material shows a high BET surface area of 78.7 m² g^-1 and a mesoporous nature with a broad pore-size distribution consisting of structural pores as well as inter-particle pores. Raman spectroscopy suggests an intimate interaction between Cu(OH)₂ and reduced graphene oxide (RGO) creating more defects by destruction of sp² domains which would help the defect-assisted charge transport during electrochemical processes. When investigated as an electrochemical supercapacitor, Cu(OH)₂@RGO shows a high capacitance of 602 F g^-1 at 0.2 A g^-1 in 1 M KOH in a three-electrode cell configuration. Detailed electrochemical studies indicate that the Faradic processes are diffusion controlled and follow a quasi-reversible kinetics. Further, a two-electrode symmetric cell shows good energy density and power density (84.5 Wh kg^-1 at 0.55 kW kg^-1 and 20.5 Wh kg^-1 at 5.5 kW kg^-1) characteristics demonstrating superior application potential of this common low-cost transition metal hydroxide for high performance energy storage devices.