Hierarchically Structured Porous Nitrogen-Doped Carbon for Highly Selective CO2 Capture

Nitrogen-doping has proven to be an effective strategy for enhancing the CO2 adsorption capacity of carbon-based adsorbents. However, it remains challenging to achieve a high doping level of nitrogen (N) and a significant porosity in a carbon material simultaneously. Here we report a facile method that enables the fabrication of ordered macroporous nitrogen-doped carbon with the content of N as high as 31.06 wt %. Specifically, we used poly(EGDMA-co-MAA) microspheres as a template to fabricate the structure which can strongly interact with melamine (the precursor of nitrogen-doped carbon framework), self-assemble into three-dimensionally ordered structure, and be easily removed afterward. Upon chemical activation, significant microporosity is generated in this material without degrading its ordered macroporous structure, giving rise to a hierarchically structured porous nitrogen-doped carbon in which a remarkable N content (14.45 wt %) is retained. This material exhibits a moderate CO2 adsorption capacity (2.69 mmol g(-1) at 25 degrees C and 3.82 mmol g(-1) at 0 degrees C under 1 bar) and an extraordinarily high CO2/N-2 selectivity (134), which is determined from the single-component adsorption isotherms based on the ideal adsorption solution theory (IAST) method. This value far exceeds the CO2/N-2 selectivity of thus-far reported carbon-based adsorbents including various nitrogen-doped ones. We believe that such an unprecedented CO2/N-2 selectivity is largely associated with the unusually high N content as well as the partially graphitic framework of this material.