Microwave-Assisted Preparation of Hierarchical N and O Co-Doped Corn-Cob-Derived Activated Carbon for a High-Performance Supercapacitor

Microwave (MW) treatment was reported as an efficient method to prepare porous carbon-based electrode material with high capacity for a high-performance supercapacitor. Herein, the superiority of the mechanism of MW treatment was tried to be revealed by preparing a N and O co-doped porous activated carbon (MWAC) based on a heteroatom-rich corn cob and compared to that of the conventional heating method. The resulting MWAC has a large specific surface area of 2508 m(2)/g with hierarchical micro- and mesoporous structures and abundant heteroatom doping of O and N. In a three-electrode system, the MWAC shows a superior specific capacitance of 560 F/g at a discharge current density of 0.5 A/g in a 6 mol/L KOH aqueous electrolyte. The symmetric supercapacitor fabricated by MWAC electrodes in a 6 mol/L KOH electrolyte shows excellent capacity retention of 96.8%, even after 10 000 galvanostatic charge-discharge cycles at the current density of 1 A/g. The aqueous (6 mol/L KOH) symmetric supercapacitor delivers a high energy density of 9.24 Wh/kg at a power density of 250 W/kg. The results prove that the MW heating shows more superiority in retaining inherent heteroatoms and creating hierarchical micro- and mesoporous structures of activated carbon for supercapacitors with high performance.

Automated summary

The N and O co-doped porous activated carbon prepared by microwave treatment exhibits a large specific surface area, excellent capacitance performance, and high energy density, showing superior capacity retention in symmetric supercapacitors. The results demonstrate that microwave heating has advantages in retaining heteroatoms and creating hierarchical micro- and mesoporous structures for high-performance supercapacitors.