N, P Co-doped hierarchical porous carbon regulated by carboxylated nanocellulose for supercapacitor

The construction of hierarchically porous carbon with a rational pore distribution using environmentally benign activators, while simultaneously incorporating heteroatom doping, is crucial for the preparation of electrode materials for supercapacitors. Here, a green one-step method has been developed that utilizes a biomass derivative, chitosan, as the matrix to construct a nitrogen-doped carbon framework, with polyethyleneimine (PEI) for synergistic nitrogen doping and hydrogen bonding interactions to optimize the carbon framework. Phytic acid (PA) is employed as a phosphorus source, activator, and crosslinker to build hierarchical porous carbon containing phosphorus doping, while carboxylated nanocellulose (CNC) is introduced to regulate the uniformity of the pore structure. The resulting HPC exhibits a specific surface area of 939.87 m²/g, a total pore volume of 0.45 cm³ /g, and a high specific capacitance of 350 F/g at a current density of 1 A/g. Furthermore, the HPC supercapacitor assembled at this current density demonstrates an energy density of 18.3 Wh/kg at a power density of 450 W/kg, with a capacitance retention rate of 86 % and a coulombic efficiency of 97 % after 10,000 cycles. Therefore, the approach in this study, which involves the use of PA to activate carbon precursors while incorporating heteroatom doping and adding CNC to promote uniform heteroatom doping, provides valuable insights for the facile, efficient, and green synthesis of biomass-based porous carbon materials, and contributes to energy storage applications.