Preparation and carbon dioxide uptake capacity of N-doped porous carbon materials derived from direct carbonization of zeolitic imidazolate framework

The preparation, characterization and CO2 uptake performance of N-doped porous carbon materials and composites derived from direct carbonization of ZIF-8 under various conditions are presented for the first time. It is found that the carbonization temperature has remarkable effect on the compositions, the textural properties and consequently the CO2 adsorption capacities of the ZIF-derived porous materials. Changing the carbonization temperature from 600 to 1000 °C, the composites and the resulting porous carbon materials possess a tuneable nitrogen content in the range of 7.1–24.8 wt%, a surface area of 362–1466 m2 g−1 and a pore volume of 0.27–0.87 cm3 g−1, where a significant proportion of the porosity is contributed by micropores. These N-doped porous composites and carbons exhibit excellent CO2 uptake capacities up to 3.8 mmol g−1 at 25 °C and 1 bar with a CO2 adsorption energy up to 26 kJ mol−1 at higher CO2 coverages. The average adsorption energy for CO2 is one of the highest ever reported for any porous carbon materials. Moreover, the influence of textural properties on CO2 capture performance of the resulting porous adsorbents has been discussed, which may pave the way to further develop higher efficient CO2 adsorbent materials.