Biomass nanoarchitectonics for porous carbon materials with exceptionally high mesoporous ratio through urea-regulated co-activation strategy and their application in supercapacitors

The synthesis of porous carbon with a high mesoporous ratio is a significant challenge, particularly when utilizing heteroatom-enriched biomass precursors as feedstock. In this work, bio-based porous carbon with a 95 % mesoporous ratio was synthesized by using chitosan and lignosulfonates as biomass precursors, combined with a urea-regulated co-activation strategy. The high mesoporous formation of porous carbon can primarily be attributed to four factors: (1) the formation of a cross-linked 3D network, (2) the generation of nitrogencontaining gas resulting from urea decomposition, (3) the depolymerization of LS and (4) KOH-activated carbonization. Besides, the specific surface area and mesoporous ratio can be adjusted by varying the ratio of KOH to urea, ranging from 1793 m2 g- 1 to 2876 m2 g- 1 and from 22 % to 95 %, respectively. The application of density functional theory calculations reveals that the synergistic effect of N/S co-doping facilitates rapid ion adsorption reactions on carbon surfaces, further improving the electrochemical performance. As carbon electrode materials for supercapacitors in a three-electrode device, the capacitance reaches up to 263 F g- 1 at 1 A g- 1. The symmetric supercapacitors fabricated using CS@LS/C-800-1:0.5 achieved an impressive energy density of 17.8 Wh & sdot;kg- 1 at a power density of 300.6 W kg- 1, along with a remarkable capacitance retention rate of 96.6 %. This strategy provides a novel insight into enhancing the mesoporous ratio of bio-based porous carbon materials, thereby significantly broadening the application scope of biomass materials.