Activated Graphene-Derived Porous Carbon with Exceptional Gas Adsorption Properties

Designing nanoporous materials with high surface area, large porosity, superior structural stability and amenability to various processing conditions, is important to meet the commercial demands of large-scale reversible gas storage systems.^{[1, 2]} Carbonaceous porous materials are particularly interesting in this respect, due to its fascinating properties, which include high surface area, high amenability to pore structure modification and surface functionalization, relative ease of regeneration, high thermal stability etc.^[3,4] Here, we demonstrate a simple approach to synthesize a highly porous activated graphene- derived carbon (a-GDC), with ultra-high surface area (~ 3240 m²g^-1) and enhanced porosity characteristics, from thermally exfoliated graphite oxide (TEGO), through an efficient and finely controlled KOH chemical activation process. Various experimental techniques including Fourier Transform-Infrared spectroscopy, High resolution Transmission Electron Microscopy and Pore size analyser are employed to characterize the materials. Detailed studies on the gas adsorption behaviour of a-GDCs have been performed at different temperatures and pressures using a volumetric gas analyser. Highly interconnected network of micro and mesopores present in a-GDC acts as active sites for adsorption of different gas molecules and outstanding gas uptake values of 21.1 mmolg^-1 (298 K, 20 bar), 11.3 mmolg^-1 (298 K, 35 bar) and 3.8 wt% (77 K, 10 bar) are obtained respectively for CO₂, CH₄ and H₂, superior to several of the other high surface area nanoporous carbon materials reported so far.^[5,6] A comprehensive comparison on the gas adsorption potential of a-GDCs with  the existing previous reports on similar and other porous materials (MOFs, COFs etc ) is also presented. In addition, good kinetics of adsorption/desorption and moderate values of heat of adsorption obtained for the a-GDC samples are particularly interesting, while its large scale commercial applications are considered. The results will draw considerable attention towards developing such materials from other cheap and easily available carbon precursors, for more effective greenhouse gas capture and gas storage applications

References

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