Self-doped N, P, O heteroatoms carbon nano-hollow-fiber derived aromatic bio-organic for advanced gravi-volumetric supercapacitors

Abstract

Abstract The combination of heteroatoms self-doping and nano-hierarchical-pore structure is essential in improving the physicochemical performance of gravi-volumetric scale supercapacitors based on biomass-derived carbon. Herein, this study used aromatic bio-organic waste from nutmeg leaves (Myristica fragrans Houtt) as raw materials due to their abundant dopant and high-potential unique nano-pore structure. A series of novel treatments were carried out using KOH immersion approach and bi-atmospheric (in N2 and CO2) pyrolysis to ensure the presence of rich heteroatoms and a defined pore structure. The results showed that KOH ratio in bi-atmospheric pyrolysis played an important role in the production of self-dopant N, O, and P. In addition, significant morphological changes were observed after the production process. The optimized material prepared at a ratio of 500 mmol g−1 showed rich heteroatoms dopant with values of 19.53%, 15.81%, and 3.01% for N, P, and O, respectively. The surface transformation of the products showed a unique structure of nano-hollow-fiber with a size of 8–12 nm size and a well-matched micro-mesopores ratio (4:1). In the 2E-symmetric system, the working electrode exhibited a high gravimetric capacitance of 235 F g−1 at 1 A g−1 and 210 F g−1 at 10 A g−1 (in H2SO4 electrolyte). The resulting energy output was relatively high at 32.64 Wh kg−1 with increased power density (218 W kg−1), coulombic efficiency (92.67%), and capacitance retention (89.78%). The findings also showed that the products obtained had a volumetric capacitance of 256.30 F cm−3 and volumetric energy of 35.00 Wh l−1. Based on these results, the selection of natural materials as well as the application of KOH immersion approach and bi-atmospheric pyrolysis produced natural self-doped N, O, P carbon nano-hollow-fiber for boosting the gravi-volumetric behavior of supercapacitors.