Template-like N, S and O tri-doping activated carbon derived from helianthus pallet as high-performance material for supercapacitors

In this study, we report a facile carbonization combined with etching strategy to synthesize N, S and O tri-doping activated carbon from biomass by-product waste - helianthus pallet. After pre-carbonization and etching with KOH, the achieved carbon material exhibits unique template-like microarchitecture and possesses high doping contents of oxygen, nitrogen and sulfur. When tested as electroactive material in supercapacitors, the optimal electrode possesses a specific capacitance of 357 F g(-1) at a current density of 0.5 A g(-1). Even cycled at 50 A g(-1) of current density, the electrode still maintains a specific capacitance of 262 F g(-1). The synergistic effect between the tri-doping elements, low etching temperature and template-like architecture is responsible for the superior electrochemical performances. The typical long cycling life, good rate capability and excellent cycling stability (similar to 98.4% capacitance retention after 10,000 cycles at 2 A g(-1)) of asymmetric supercapacitor endow the present bio-waste based material a promising application value in supercapacitors.