Preparation and Electrochemical Performance Study of Covalent Organic Framework-Derived Porous Carbon@FeS2

Abstract

Covalent organic frameworks (COFs) offer designable skeletons and ordered pore domains, but poor charge transport and insufficient electrochemically active sites hinder their direct use as electrodes. In this work, COF-Bq was first obtained by Knoevenagel condensation and then transformed by carbonization and KOH activation into COF-BqC-700-3. A hydrothermal step grew FeS₂ within and on this porous carbon, giving COF-BqC-700-3@FeS₂ composites. The optimized COF-BqC-700-3@FeS₂-160-2 maintained hierarchical porosity dominated by micropores and reached 740.2 F g⁻¹ at 1 A g⁻¹. When assembled with COF-BqC-700-3 in an asymmetric device, it delivered 25.03 Wh kg⁻¹ at 750 W kg⁻¹. The device retained 90.95% capacitance after 5,000 cycles and showed 99.93% Coulombic efficiency. These results show that FeS₂ adds Faradaic storage sites to COF-derived carbon while the porous carbon framework supports charge transfer and ion transport.

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