Tuning the pore structure and surface chemistry of porous graphene for CO2 capture and H2 storage

Porous graphene materials (PGMs) have been fabricated through CO2 and KOH activation of thermal exfoliated graphite oxide. The CO2 activated PGMs (CPGMs) display a three-dimensional morphology with hierarchical pore structure, while the KOH activated PGMs (KPGMs) exhibit a two-dimensional sheet morphology with numerous micropores and small mesopores. By adjusting the activation conditions, their specific surface areas and pore volumes can be easily tuned in a wide range. Moreover, the as-prepared PGMs show various surface chemistry, in which the CPGMs own a high content of quinone and carbonyl groups, and the KPGMs possess abundant hydroxyl groups. Gas adsorption experiments demonstrate that CO2 and H-2 uptakes of PGMs are affected by both their pore structure and surface chemistry. Notably, the KPGMs-7 has the highest CO2 uptake of 17.87 wt% (4.06 mmol g(-1)) at 273 K and 1 bar and H2 uptake of 2.41 wt% (11.88 mmol g(-1)) at 77 K and 1 bar, respectively.

Automated summary

Porous graphene materials (PGMs) with different morphologies and pore structures can be prepared through CO2 and KOH activation of thermal exfoliated graphene oxide, exhibiting rich surface chemistry properties. The specific surface areas and pore volumes of PGMs can be easily tuned by adjusting the activation conditions, affecting their gas adsorption performance significantly. Experiment results demonstrate that the gas adsorption of PGMs is influenced by both their pore structure and surface chemistry, showing potential applications in gas storage and separation technologies.