Influence of chemical functionalization on the CO2/N2 separation performance of porous graphene membranes

Abstract

The separation of CO₂ from a mixture of CO₂ and N₂ using a porous graphene membrane was investigated using molecular dynamics (MD) simulations. The effects of chemical functionalization of the graphene sheet and pore rim on the gas separation performance of porous graphene membranes were examined. It was found that chemical functionalization of the graphene sheet can increase the absorption ability of CO₂, while chemical functionalization of the pore rim can significantly improve the selectivity of CO₂ over N₂. The results show that the porous graphene membrane with all-N modified pore-16 exhibits a higher CO₂ selectivity over N₂ (∼11) due to the enhanced electrostatic interactions compared to the unmodified graphene membrane. This demonstrates the potential use of functionalized porous graphene as single-atom-thick membrane for CO₂ and N₂ separation. We provide an effective way to improve the gas separation performance of porous graphene membranes, which may be useful for designing new concept membranes for other gases.

Molecular Dynamics Study on the Effect of Surface Hydroxyl Groups on Three-Phase Wettability in Oil-Water-Graphite Systems

“…The structures of the oil and water molecules are shown in Figure 1b. For the hydroxylated graphite system, hydroxyls are arranged uniformly on the first layer of the graphite surface to modify the graphite [20]. Figure 1c shows the local configuration of the hydroxylated graphite surface.…”

Environmental applications using graphene composites: water remediation and gas adsorption

“…221 Various other theoretical studies have elaborated on the use of graphene porous membranes in gas phase separation. 152,[222][223][224][225] These studies focus on the functionalization of the pores and/or changing the pore size to enhance the gas phase separation efficiency, as such synthetic methods that can produce these nanostructures are very important. An interesting theoretical study by Brockway and Schrier has shown that a graphene membrane model based on a previously synthesized graphene porous membrane can be used to separate He from natural gas.…”

“…The authors showed that these membranes selectively lter the gas mixture by preferably adsorbing one species over the other. 152 By using DFT and molecular dynamics simulations Carrillo et al studied the adsorption of CO 2 on a Ti-graphene system with high metal coverage. 153 It was shown that the positive charge carrying Ti atoms on graphene surfaces attract negatively charged oxygen atoms towards the graphene surfaces, thereby dominating the initial repulsion of the C atom by the Ti atoms.…”

“…[151][152][153][154] Wood and Pathak used DFT to determine the geometry and energetics of CH 4 and CO 2 adsorbed on zigzag graphene nanoribbons (ZGNRs) with attached chemical functional groups. 151 The authors showed that polar groups (COOH, NH 2 , NO 2 , and H 2 PO 3 ) are promising candidates for enhancing CO 2 and CH 4 adsorption capacity by strengthening adsorption and activating exposed edges and terraces to introduce additional binding sites.…”

Bilayer Graphene Membrane for Hydrogen Separation: Insights from Molecular Dynamics

“…Therefore, graphene and related materials it derives are considered as excellent membrane materials in gas separation applications by its nature of single-atom thickness [4]. So far, most studies have considered an idealized, single-layer system with variations in several key parameters, such as nanopore size or chemical modification [5,6]. Zhu and his coworkers have demonstrated that C 2 N monolayer with 3.0 Å pore size showed an exceptionally high selectivity for He/Ne (Ar, CH 4 , CO 2 , N 2 , et al) in a wide range of temperature [5].…”