Aminated lignin derived sub-nanometer porous N-doped carbon via a low-corrosion grafting-activation strategy for CO2 capture and energy storage

The synergistic introduction of sub-nanometer pores (< 1 nm) and nitrogen doping is crucial for high-performance activated carbon (AC) in applications such as CO 2 adsorption and electrochemical systems. However, simultaneously achieving both features remains challenging, as pore formation and nitrogen incorporation often exhibit an inverse relationship during activation. Herein, we report a novel amination-activation strategy that concurrently engineers both features into biomass-derived AC. Critically, chemical grafting of urea onto lignin (UR-L) prior to pyrolysis enables a triple function, serving as carbon source, self-templating pore-former, and nitrogen dopant, which is distinct from simple physical mixing of urea and lignin. Compared to ACs from physically mixed urea/lignin, the optimized UR-L-700–0.5 K exhibits 37.7% higher sub-nanometer pore content, enhanced pyrrolic-N speciation, and superior CO 2 capacity (4.67 vs. 3.92 mmol g −1 at 298 K, 1 bar). When configured as a symmetric supercapacitor, it delivered a specific capacitance of 60.2 F g −1 and an energy density of 26.12 W h kg −1 , substantially exceeding YP-50F. Notably, KOH consumption was reduced by over 50% compared to conventional activation methods, underscoring the economic and environmental benefits of this strategy. • Sub-nanometer pores and N species play a key role in AC applications. • Amination-activation strategy enables sub-nanometer pore formation and N-doping. • Urea-grafted lignin (UR-L) achieves > 50% reduction in KOH consumption. • UR-L-700–0.5 K shows 4.67 mmol/g CO 2 uptake and 26.12 W h/kg for energy storage.