High-performance supercapacitors prepared on the base of nitrogen-doped tubular porous carbon from polypyrrole coated Juncus effusus

Renewable biomass-derived carbon materials are beneficial for the sustainable development of energy. Herein, we propose a strategy to fabricate nitrogen-doped tubular porous carbon (PPy@JEC) by depositing Polypyrrole (PPy) on the surface of Juncus effusus (JE) microtubes and then carbonizing and activating with KOH. Changing the activation temperature and dosage of the activator could effectively regulate the pore structure of PPy@JEC. Such tubular porous carbon retains JE's natural microtubule structure for improving electrolyte ions transfer efficiency. The optimal carbon materials exhibited a high specific surface area (1955 m2 g−1), good electrochemical performance (326 F g−1 at 0.5 A g−1), and the capacitance retention reached 66 % at 20 A g−1. The symmetric supercapacitor constructed using the optimal PPy@JEC exhibits an energy density of 15 Wh kg−1. The capacitance retention rate can remain 90.9 % after 15,000 cycles at 5 A g−1. This work demonstrates that PPy@JEC can be a potential candidate for low-cost and sustainable supercapacitor electrode materials.