Hierarchical porous graphene-based carbons prepared by carbon dioxide activation and their gas adsorption properties

• Facile synthesis of hierarchically micro-meso-macroporous graphene-based carbons.
• Modulated microstructures in graphene-based carbons are shown.
• A formation mechanism for the hierarchical porous structure is proposed.
• The graphene-based carbons show significant adsorption capacities for CO2 and H2.

Hierarchical porous graphene-based carbons (HPGCs) have been prepared by a simple carbon dioxide activation of graphite oxide. The effects of activation temperature on the structural and textural properties as well as gas adsorption capacities of the resultant carbons have been investigated. The HPGCs showed hierarchically micro-meso-macroporous structures, high specific surface areas of up to 532 m2 g−1, and large pore volumes of up to 1.67 cm3 g−1. Moreover, the HPGC materials were demonstrated to be efficient for CO2 and H2 adsorption. The HPGC-850, which was obtained after two hours of activation at 850 °C, exhibited the highest adsorption capacities of 7.74 wt% (1.76 mmol g−1) at 273 K and 1 bar for CO2 and of 0.75 wt% (3.76 mmol g−1) at 77 K and 1 bar for H2.