Sustainable mechanochemical production of amino graphene for enhanced electrothermal carbon dioxide capture

Abstract Graphene-based materials are particularly attractive for electrothermal swing adsorption (ETSA)-driven CO 2 capture because of their exceptional electrical and thermal conductivities. However, the intrinsic chemical inertness of pristine graphene hinders preferential CO 2 binding from gas mixtures, yielding low adsorption capacity and poor selectivity. In addition, the scalable production of functional graphene for industrial-level CO 2 capture remains a critical challenge. Herein, polyamine-assisted mechanochemistry (PAME) is demonstrated as an impactful and scalable approach for producing ultrathin graphene nanosheet-polyethyleneimine (GNs-PEI) composites. Density functional theory (DFT) calculations reveal strong binding interactions of 0.183 J/m 2 between graphite and polyamine, which facilitate simultaneous exfoliation and functionalization during the PAME process. The yielded GNs-PEI exhibits a high aspect ratio of 201 and an amine content of approximately 38.23 wt%. The GNs-PEI exhibited a CO 2 adsorption capacity of up to 4.77–3.44 mmol/g and a selectivity of 386 − 122 under simulated flue gas conditions (CO 2 /N 2 ratio of 15/85) at 25–55 ℃, respectively. Furthermore, GNs-PEI achieved dynamic CO 2 capacities of 3.06–3.62 mmol/g (dry) and 3.37–4.21 mmol/g (85% RH) at 25 and 50 ℃, suitable for industrial post-combustion capture. Also, the GNs-PEI demonstrated wonderful cyclic stability, retaining over 88.8% of its initial adsorption capacity after 50 temperature-swing adsorption-desorption cycles. Under a simulated ETSA process, GNs-PEI foam showed a prominent heating rate of 1.43 ℃/s at an applied bias of 8 V.