Nitrogen and Oxygen Co‐Doped Porous Carbon Tubes with Fast Ion Diffusion Channel for Supercapacitor

The green idea of “reducing waste” is the basis of this study, which used Physalis peruviana L. husks from agricultural waste as a precursor. A nitrogen‐oxygen co‐doped porous carbon (PPC‐600) was successfully created using a one‐step activation technique with potassium oxalate. This material inherits the original tubular morphology of biomass and forms rapid ion diffusion channels dominated by micro/mesopores. In a three‐electrode system (6 M KOH electrolyte), PPC‐600 showed a high specific capacitance of 431.3 F g −1 at a current density of 0.5 A g −1 . It was still able to maintain 314.7 F g −1 at a large current density of 20 A g −1 , indicating excellent rate performance. After 10,000 cycles, its capacitance retention rate reached 100.6%. Furthermore, the PPC‐600//PPC‐600 symmetric supercapacitor (2 M ZnSO 4 electrolyte) attained a high energy density of 28.7 Wh kg −1 and maintained 89.3% of its initial capacity after 10,000 cycles. This work created an avenue for the high‐value utilization of Physalis peruviana L. husks and offered useful references for the creation of sustainable and high‐performing carbon‐based materials.