Self-Doped Hierarchical Porous Carbon Derived From Mixed Chinese Herbal Medicine Residues for High Performance Supercapacitors.

Porous carbons (YZPCs) with self-doped heteroatoms (oxygen and nitrogen) were successfully prepared from mixed Chinese herbal medicinal residues via a simple KOH activation process under a nitrogen atmosphere. The resulting carbon exhibits a high specific surface area of 3359 m²·g⁻¹ and a hierarchical pore structure, which together provide abundant active sites for charge storage and facilitate rapid ion transport. Moreover, the substantial pseudocapacitance derived from the self-doped heteroatoms (N: 1.89 at%; O: 16.11 at%) further enhances the overall specific capacitance. The corresponding electrode delivers a specific capacitance of 344 F·g⁻¹ at 1 A·g⁻¹, 270 F·g⁻¹ at 10 A·g⁻¹, along with excellent cycling stability (96% capacitance retention after 10,000 cycles at 10 A·g⁻¹). Overall, this study demonstrates the potential of the proposed method as an effective and low-cost approach to fabricate high-performance supercapacitors.