COF-derived hierarchical porous N,O dual-doped carbon nanosheets towards efficient aqueous Zn-ion supercapacitor with long lifespan

Designing and precisely constructing novel carbon-based cathodes with a high specific surface area (SSA), excellent stability, and abundant active sites is critical for achieving high-performance zinc-ion hybrid capacitors (ZHCs). Covalent organic frameworks (COFs), a class of well-defined crystalline porous polymer materials, can integrate organic building blocks into highly ordered topological structure, offering a robust platform for specific structural design and versatile functional exploitation. In this study, hierarchical porous carbon nanosheets (PCs) with high conductivity and abundant heteroatom doping were synthesized through an in situ polycondensation reaction followed by high-temperature carbonization. This unique structure facilitates the diffusion of electrolyte ions and the adsorption/desorption of Zn²⁺ ions. As a result, the optimized PC-1000 electrode demonstrates a high specific capacity of 168.9 mAh g⁻¹ at 0.1 A g⁻¹ and remarkable stability, maintaining a high capacity retention rate of 102.5 % after more than 50,000 cycles at 10 A g⁻¹, outperforming other PC-based materials reported in the literature. This work provides an effective way for developing carbon-based cathode materials for high-performance energy storage devices.