Design and fabrication of carbonized rGO/CMOF-5 hybrids for supercapacitor applications

Abstract

A reduced graphene oxide/carbonized metal–organic framework (rGO/CMOF-5) hybrid with an rGO inner layer and an outer cover of CMOF-5 was successfully fabricated by combining a simple solvothermal reaction with an annealing treatment. The resulting rGO/CMOF-5 hybrid had a high specific surface area (2040 m² g⁻¹) and a reasonable porous structure and showed improved electrochemical performance when used as a novel supercapacitor electrode material. Electrochemical tests showed that the rGO/CMOF-5 hybrid achieved an impressive specific capacitance of 312 F g⁻¹ at a current density of 0.5 A g⁻¹ in an alkaline electrolyte and an outstanding cycle stability (retaining 89% capacitance after 5000 cycles) and favorable rate capability with 59% retention after a 40-fold increase. A symmetrical supercapacitor based on the rGO/CMOF-5 hybrid delivered a high energy density of 17.2 W h kg⁻¹ at a power density of 250 W kg⁻¹ and retained 81% of its initial capacitance at a current density of 2 A g⁻¹ after 5000 charge–discharge cycles. These results indicate that this hybrid could be used in electrochemical energy storage and gave new insights into the design and utilization of aged carbon materials with remarkable performances.