Simulations on methane uptake in tunable pillared porous graphene hybrid architectures

Extended Line Defect Graphene Modified by the Adsorption of Mn Atoms and Its Properties of Adsorbing CH4

Extended line defect (ELD) graphene is a two-dimensional (2D) topologically defective graphene with alternate octagonal and quadrilateral carbon rings as basic defective units. This paper reports on the CH4 adsorption properties of ELD graphene according to the first principles of density functional theory (DFT). The effects on the CH4 adsorption of ELD graphene when modified by a single Mn atom or two Mn atoms were investigated, respectively. An ELD-42C graphene configuration consisting of 42 C atoms was first constructed. Then, the ELD-42C graphene configuration was used as a substrate, and a Mn-ELD-42C graphene configuration was obtained by modifying it with a single Mn atom. The results showed that the most stable adsorption site for Mn atoms was above the quadrilateral carbon ring. This Mn-ELD-42C graphene configuration could only stably adsorb up to 30 CH4 molecules on each side, with an average adsorption energy of -0.867 eV/CH4 and an adsorption capacity of 46.25 wt%. Three 2Mn-ELD-42C graphene configurations were then obtained by modifying the ELD-42C graphene substrate with two Mn atoms. When the two Mn atoms were located on either side of a 2Mn-ELD-42C graphene configuration and above the two octagonal carbon rings adjacent to the same quadrilateral carbon ring, it was able to adsorb up to 40 CH4 molecules on each side, with an average adsorption energy of -0.862 eV/CH4 and a CH4 adsorption capacity of 51.09 wt%.

Grand canonical Monte Carlo simulations of methane adsorption in fullerene pillared graphene nanocomposites

The objective of this study is to investigate the methane adsorption performance of fullerene pillared graphene nanocomposites (FPGNs) with adjustable micro and meso porous morphology and high surface/weight ratios. Different types of fullerenes are considered as pillar units to adjust the porosity of FPGNs. The gravimetric, volumetric and deliverable methane storage capacities of FPGNs are examined using grand canonical Monte Carlo (GCMC) simulations. The lithium doping strategy is also employed to further improve the methane adsorption performance of FPGNs. GCMC simulations revealed that FPGNs have promising potential for methane storage applications with the appropriate selection of design parameters. In particular, the simulation results demonstrated that the gravimetric absolute methane uptake of FPGNs could reach 12.5 mmol/g at 298 K and 40 bars and, this value could be increased up to 19.7 mmol/g with appropriate doping ratio under the same conditions.

Gas separation using graphene nanosheet: insights from theory and simulation

The investigation of porous graphene, especially experimental research, is a challenging issue in related academic and technology and has become a hot topic in recent years. It is well known that the preparation of porous graphene is a difficult problem in experimental techniques. To prepare nanoporous graphene, much attention must focus on the quality of nanoporous structures and throughput array pores. Therefore, a comprehensive summary as much as possible has been made to provide a better understanding of the progress. A summary of synthesis techniques, the properties of nanoporous graphene membranes from the synthesis point of view, and potential applications of porous graphene and graphene oxide for gas separation on the basis of theoretical studies were given attention in this paper. Gas separation, including carbon dioxide capture, gas storage, natural gas sweetening, and flue gas purification through porous graphene, is of great interest. Porous graphene with narrow pore distribution provides exciting opportunities in gas separation processes.