Copper-nickel rubeanate metal-organic framework, a new highly stable and long active life nanocomposite for high-performance supercapacitors

Abstract

High-performance supercapacitors require electrodes featuring a high surface area, suitable porosity, and conductivity. Metal-organic frameworks (MOFs) hold a high surface area and suitable porosity while insufficient conductivity. Herein, a single-step chemical strategy was developed to directly synthesize a composite of copper-nickel rubeanate MOF and highly conductive reduced graphene oxide (rGO) nanosheets (CNRG-MOF) on nickel foam (CNRG-MOF/NF) electrode. The nanocomposite enables it to use as a high-performance supercapacitor electrode. The bimetallic CNRG-MOF/NF electrode exhibits superior electrochemical performance than its single metallic counterparts. The optimized CNRG-MOF/NF electrode represents a high specific capacitance of 846.15 F g−1 at a current density of 1.0 A g−1. A three-electrode system exhibited up to 96.37 % capacitance retention after 7000 galvanostatic charge-discharge (GCD) cycles, indicating its excellent stability. These results may pave the way for the direct use of MOF materials for electrochemical energy devices instead of pyrolyzing the MOFs to improve the conductivity while losing controllable structural merits. GCD curve was obtained at different current densities to evaluate the nanocomposite's asymmetric setup charge storage capability. The electrode capacity for the asymmetric system was measured as 93.3 F g−1, which proves the capacitive property of CNRG-MOF/NF electrode.