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

Abstract

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.