Exploring the intrinsic properties of a melamine-based covalent organic framework/nitrogen-doped reduced graphene oxide composite for advanced supercapattery applications

The quest to improve the efficiency of energy storage systems has stimulated the exploration of new materials with intrinsic characteristics that are beneficial for increasing their electrochemical performance. In this study, a metal-free melamine-based COF decorated on nitrogen-doped reduced graphene oxide (mCOF/NrGO composite) was synthesized through a simple impregnation method at room temperature and applied as an electrode material for supercapattery application. From the BET analysis, mCOF displayed a notably high specific surface area of 142.09 m 2 /g, a pore volume of 0.588 cm 3 /g, and a pore diameter of 11.18 nm, which are essential for ion transport and charge migration. TGA of the NrGO demonstrated good structural and thermal stability, which is essential for long-term cycling. Based on the observed synergistic effect of the mCOF and NrGO, the mCOF/NrGO composite displayed excellent maximum specific capacity of 387C/g (at 2.0 A/g current density) and 191C/g (at scan rate: 40 mV/s) as derived from the GCD and CV, respectively, as compared to its precursors in a three-electrode system. Further, an asymmetric cell configuration with mCOF/NrGO as the positive electrode and AC as the negative electrode (i.e., AC//mCOF/NrGO) has shown an energy density of 7 Wh/kg at a power density of 225 W/kg and a current density of 0.3 A/g. The results obtained are in good agreement with the computational studies, in which the mCOF/NrGO composite exhibited the highest quantum capacitance (C q ) of 1944 μF/cm 2 . Generally, this work demonstrates the potential of a metal-free 3D COF material as an essential precursor for high-performance supercapacitors, as it possesses mesopores that prevent restacking of the NrGO nanosheets, enabling sufficient interfacial ion transfer.