Green synthesis of nitrogen, sulfur-co-doped worm-like hierarchical porous carbon derived from ginger for outstanding supercapacitor performance

Herein, we report a low cost, green synthesis of unique hierarchical worm-like porous co-doped thin carbon nanosheets from ginger as biomass source using non-toxic NaCl/KCl salt mixture as activation media (unlike conventional toxic activation agents like KOH) for high performance supercapacitor application. The optimized synthesis of Nitrogen, Sulfur-doped activated ginger carbon (DAGC) exhibits micro-meso-macro porous structure, facilitating efficient electrolyte diffusion, appropriate graphitization degree, enhanced surface wettability, and synergistic effects between co-doped heteroatoms for rapid ion transfer. Transmission electron microscope (TEM) and Raman spectroscopy studies reveal the partially graphitized walls of carbon and graphitization degree respectively. The DAGC electrode exhibits an excellent specific capacitance of 456 F g(-1) at 0.3 A g(-1) in three-electrode cell. The assembled symmetric DAGC//DAGC supercapacitor delivers an outstanding specific energy of 48.3 Wh Kg(-1) at 400 W kg(-1) in comparison to other reported porous carbon with traditional activation method. Moreover, the DAGC supercapacitor device works in high potential region (0-1.4 V) with 1 M Na2SO4 as supporting electrolyte, exhibiting an excellent rate capability and high cyclic stability of 95% after 10000 cycles. All these features of DAGC electrode material make it environment friendly and a competitive entrant for electroactive materials in wide range of applications. (C) 2020 Elsevier Ltd. All rights reserved.