Transforming waste sugar solution into N-doped hierarchical porous carbon for high performance supercapacitors in aqueous electrolytes and ionic liquid

Abstract Waste sugar solution is a by-product in the process of manufacturing vitamin C. Nowadays, the unused industrial waste residues are transformed into high efficient energy storage devices, such as supercapacitors electrodes, which are worth exploring because they are consistent with the concept of green and sustainable development. In this paper, a nitrogen-doped hierarchical porous carbon are obtained via pre-carbonization and KOH activation. The as-prepared material, possessed proper pore size distribution, large specific surface area and nitrogen-doping, exhibits good electrochemical performance, such as a high specific capacitance of 342 F g−1 (0.1 A g−1), good stability with 95% capacitance retention after 15,000 cycles in 6 M KOH. Moreover, the supercapacitors deliver a high energy density of 25.6 and 65.9 W h kg−1 in the 1 M Na2SO4 and EMIMBF4, respectively. The good electrochemical performance illustrates that the nitrogen-doped hierarchically porous carbon derived from the waste sugar solution is a potential candidate for energy storage.