Facile synthesis of copper hexacyanoferrate/graphene nanocomposite for electrochemical energy storage

A two-component nanocomposite of copper hexacyanoferrate/reduced graphene oxide (CuHCF/rGO) was successfully synthesized using a solution-based co-precipitation process in the presence of graphene oxide solution. Electrochemical measurements indicated a specific capacitance of 548 F g(-1) at a current density of 0.5 A g(-1) in the potential range of -0.2 to 1 V, versus Ag/AgCl standard electrode, obtained in an electrolyte of 0.5 M K2SO4 (as a neutral electrolyte) during galvanostatic charge/discharge cycles. This value is higher than the specific capacitance of the raw materials rGO (174 F g(-1) at a current density of 0.5 A g(-1)) and CuHCF (236 F g(-1) at a current density of 0.5 A g(-1)), which is rooted in the activation of copper ions in the electrochemical reaction and some synergistic effects (observed between rGO and CuHCF). The rGO/CuHCF nanocomposite electrode was able to retain 83% of its initial capacitance after 1000 cycles at a current density of 3 A g(-1).