Rational design of pyrene-based metal-free covalent organic frameworks for supercapacitor applications

Abstract

Rationally designed covalent organic frameworks (COFs) have garnered attention as advanced electrode materials for energy storage due to their ordered π-conjugated network, porous framework, and excellent stability. Judicious selection of redox-active organic moieties for COFs may impart intrinsic redox properties, efficient charge transfer, and high electrical conductivity, enabling high-performance supercapacitors. Considering this, a series of pyrene-based donor–acceptor COFs were prepared using porphyrin, pyrene, and diarylamine as π-conjugated monomers. While pyrene serves as the primary electron-donor unit in each COF, porphyrin and diarylamine moieties act as redox-active electron-acceptor sites, forming a donor–acceptor architecture within the COFs to enhance redox capability and ion transport, thereby enhancing the framework's electrochemical activity. Each COF exhibits a long-range ordered structure with high porosity and has been further investigated for supercapacitor applications. Among them, the porphyrin-incorporated COF exhibited high capacitive behavior, delivering a maximum specific capacitance of 178 F g−1 at a current density of 3.5 A g−1 with >90% retention of capacitance after 9000 cycles in a three-electrode setup. Additionally, the asymmetric device for the porphyrin-based COF showed a specific capacitance of 47 F g−1 at 0.75 A g−1, with an energy density of 14.7 Wh kg−1 and a power density of 583 W kg−1. The high performance of the porphyrin-based COF is rationalized by a crystalline porous network, redox-active sites, and a donor–acceptor architecture, which enable efficient ion diffusion and rapid electron transport during charge–discharge processes. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique, 2026.