Novel Nitrogen-Doped Porous Carbons Derived from Graphene for Effective CO₂ Capture

In this work, graphene-derived N-enriched porous carbons were synthesized by urea modification and KOH activation of thermally shocked graphene oxide. The prepared sorbents were characterized by various techniques and investigated as potential CO₂ capture materials. The as-prepared sorbents possess high CO₂ adsorption capacity of 2.40 mmol/g (25 °C) and 3.24 mmol/g (0 °C) at 1 bar, which is higher than most graphene-based carbons reported previously. The nitrogen incorporation and narrow microporosity are the two major factors that determine CO₂ uptake for these graphene-derived carbonaceous adsorbents under ambient conditions. The adsorption kinetic data of the optimized sample were well-described by the classical Fick’s diffusion model with a high CO₂ diffusion rate. The fast CO₂ adsorption kinetics can be attributed to the short diffusion paths of this sample, which is composed of thin layers of graphene sheets. Moreover, these graphene-derived sorbents also demonstrate excellent stability and recyclability, high selectivity of CO₂ over N₂, suitable heat of adsorption, and excellent dynamic CO₂ capture capacity. As a result, these graphene-derived porous carbons deserve consideration for removal of CO₂ from exhausted flue gas.