Biomass-based Self-single-oxygen Heteroatom-doped Hierarchical Porous Carbon Nanosheets for High-performance Symmetrical Supercapacitors

Biomass-based porous carbon holds potential for improving the electrochemical performance of supercapacitors due to its high surface area, 2D nanostructure, 3D hierarchical pores, and self-multi-doped-heteroatoms. Here, 2D and 3D porous carbon nanostructures, as well as self-single-doped oxygen were successfully obtained from Moringa oleifera leaves waste by a facile, time-saving, and cost-effective strategy. The dried powder precursor was chemically provided with 0.5 m/L H3PO4 and ZnCl2 solutions at high-temperature pyrolysis. Furthermore, electrode material was designed with sleekly slim binder-free solid coins. The obtained porous carbon has a 2D nanosheet-nanofiber and rich-3D hierarchical porous structure with significantly high sub-ultra micropores. Meanwhile, 17.62 % self-doped oxygen was found to provide an extra pseudocapacitance effect. The optimum carbon possessed high electrochemical properties at a specific capacitance of 201 F g(-1) in 1 M H2SO4 electrolyte. Furthermore, the maximum energy density was obtained at 25 Wh kg(-1), at optimum power of 122 W kg(-1) in current density of 1.0 A g(-1). The electrochemical behavior of these samples was also reviewed through a 1 M Na2SO4 neutral aqueous electrolyte. Therefore, the great potential of Moringa oleifera leaves was observed as a porous carbon source with good material properties for enhancing the performance of electrochemical energy storage devices.