N-doped porous carbons from low-temperature and single-step sodium amide activation of carbonized water chestnut shell with excellent CO2 capture performance.

Graphical abstract Highlights • N-doped porous carbons were synthesized by one-step NaNH 2 activation of carbonized water chestnut shell. • The activation temperature ranges from 400 to 500 °C. • Water chestnut shell derived carbon exhibits high CO 2 uptake, 4.5 mmol/g at 25 °C and 1 bar. • N-doped porous carbons adsorbed CO 2 rapidly and had excellent cyclability. • Nitrogen content, pore size and volume of narrow micropore are key factors in determining CO 2 uptake. Abstract The aim of this study is to exploit low-cost N-doped porous carbonaceous adsorbents with excellent CO 2 adsorption properties. Herein, the N-enriched porous carbons were obtained through a single-step sodium amide activation of carbonized water chestnut shell at 400–500 °C. The optimal sample possesses high CO 2 uptake of 4.50 mmol/g (25 °C) and 6.04 mmol/g (0 °C) at atmospheric pressure. Additionally, this sample displays high CO 2 /N 2 selectivity, stable cyclic ability, moderate CO 2 isosteric heat of adsorption, fast CO 2 adsorption rate, and high dynamic CO 2 uptake. In addition to the two well-known factors i.e. volume of narrow micropore and N content, the pore size distribution is also found to play major role in deciding CO 2 adsorption performance for these adsorbents. The features of excellent CO 2 adsorption properties, low-cost raw materials, low reaction temperature and facile preparation demonstrate that these adsorbents are prospective in the application of CO 2 capture. [ABSTRACT FROM AUTHOR]