Large-sized and ultrathin biomass-derived hierarchically porous carbon nanosheets prepared by a facile way for high-performance supercapacitors

In this paper, we propose a one-step and low-cost strategy to synthesize nitrogen/phosphorus co-doped large-sized and ultrathin carbon nanosheets derived from chitosan. The harmless sodium hypophosphite is applied as phosphorus source instead of phosphate, and manganese nitrate is used as the activator and mesoporous template in the synthesis process. More importantly, a small amount application of sodium hypophosphite can make an optimal structure than other work and therefore exhibit better electrochemistry performance. Manganese nitrate shortens the synthesis step and help form reasonable hierarchical porous structure without hard templates. The as-prepared nanosheets not only present effective heteroatoms doping concentration to offer more defects and active sites, but also obtain favorable large-sized and ultrathin hierarchical pore structure for the electrolyte ion adsorption and transportation, which improves the capacitive performance effectively. We further illustrate the mechanism of the sodium hypophosphite on the formation of nanosheets and manganese nitrate as activators. The approach that we proposed will inspire the exploration of more variable biomass-derived porous carbon materials for the synthesis of large-sized and ultrathin carbon nanosheets structure.