Two-Dimensional Porphyrin-Based Covalent Organic Frameworks/g-C3N4 Composites as High-Performance Supercapacitor

Covalent organic frameworks (COFs) with high porosity and redox-active properties have been advanced as electrode materials for energy storage systems, although poor electron conductivity and inaccessibility of active pore sites hinder their performance as electrode material for supercapacitor application. Thus, incorporation of a COF with various conductive materials can be an effective strategy to improve their electrochemical performances for supercapacitors. Herein, we report the synthesis of POR-COF@g-C₃N₄ composites by fabricating a porphyrin-based COF on g-C₃N₄ via in situ solvothermal conditions. A series of COF composites, known as POR-COF@g-C₃N₄-X, were prepared by incorporating different ratios of COF (X = 10%, 20%, 30%, and 40%) into g-C₃N₄ and investigated as electrode materials for supercapacitor performance. The optimized COF composite (POR-COF@g-C₃N₄-30) achieved a specific capacitance of 788 F g^-1 at 4 A g^-1, much higher compared to pristine COF. Further, the asymmetric device assembled using POR-COF@g-C₃N₄-30 demonstrated a high energy density of 24.4 Wh kg^-1 at a power density of 1152 W kg^-1 and a long-term cycling life of 74% capacity retention after 6000 cycles. Our work highlights the scope of COF-based composites as active electrode materials for highly efficient supercapacitor performance.