Biomass-derived nitrogen-doped porous carbon with superior capacitive performance and high CO2 capture capacity.

Nitrogen-doped porous carbon is synthesised through a low-cost approach that utilise water chestnut as a carbon source and melamine as a nitrogen source through potassium hydroxide (KOH) activation for 2 h at 600 °C-900 °C. The obtained samples exhibit predominant characteristics with highly developed micropores, an ultralarge specific surface area (3401 m 2  g −1 ) and a high nitrogen content (4.89 at.%). These characteristics endow nitrogen-doped porous carbon with a high specific capacity of 346 F g −1 and a high energy density of 22.4 W h kg −1  at 0.5 A g −1 in 6 mol dm −3 KOH. It also exhibits an excellent cycling stability with a retention of nearly 97.6% capacity after 5000 cycles at 1 A g −1 . In addition, the unique pore structure and high nitrogen content of porous carbon provide an important contribution to CO 2 adsorption capacity, which can reach up to 6.0 mmol g −1 (at 0 °C and 1 bar) and 4.7 mmol g −1 (at 25 °C and 1 bar), and to high CO 2 /N 2 selectivity. Results show that the synthesised porous carbon exhibit considerable potential in electrochemical energy storage and solid adsorption. [ABSTRACT FROM AUTHOR]