Ionic Liquid Selectively Facilitates CO₂ Transport through Graphene Oxide Membrane

Abstract

Membrane separation of CO from H, N, or CH has economic benefits. However, the trade-off between selectivity and permanence in membrane separation is challenging. Here, we prepared a high-performance CO-philic membrane by confining the [BMIM][BF] ionic liquid to the nanochannels in a laminated graphene oxide membrane. Nanoconfinement causes the [BMIM][BF] cations and anions to stratify. The layered anions facilitate CO transportation with a permeance of 68.5 GPU. The CO/H, CO/CH, and CO/N selectivities are 24, 234, and 382, respectively, which are up to 7 times higher than that of GO-based membranes and superior to the 2008 Robeson upper bound. Additionally, the resultant membrane has a high-temperature resistance, long-term durability, and high-pressure stability, indicating its great potential for CO separation applications. Nanoconfining an ionic liquid into the two-dimensional nanochannels of a laminated membrane is a promising gas separation method and a nice system for investigating ionic liquid behavior in nanoconfined environments.

Boron Nitride Membranes with a Distinct Nanoconfinement Effect for Efficient Ethylene/Ethane Separation

“…After nanoconfinement of RIL into BN membrane,a ll the characteristic peaks of RIL and BN show red-shifts (Figure 3c;S upporting Information, Figure S12), which are indicative of the hydrogen bond and p-p stacking interactions between RIL and BN nanochannel walls.I ts hould also be noted that the red-shift of the IL cation is larger than that of anion, which indicates that cation-BN interaction is stronger than that of anion-BN interaction. Similar to recent studies on ILs confined in carbon nanopores, [19] the nanoconfinement of RIL within BN nanochannels cripples the Coulomb force between cation and anion. As seen from the snapshots of the simulation box (Figure 3d), the ordered nanostructure of RIL is clearly discernable:a lkyl groups of the cations are aggregated together to construct apolar regions,w hich are separated from each other by intervening polar regions of aggregated NO 3 À anions.T he silver ions are solvated exclusively in the polar regions and are physically connected along the dimensions of the BN nanochannels.As seen from Figure 3e,t wo main peaks of cations are located next to the BN walls owing to the stronger non-covalent interactions between cation and BN nanosheets,w hile two minor cation peaks are located near the center.…”

Boron Nitride Membranes with a Distinct Nanoconfinement Effect for Efficient Ethylene/Ethane Separation

“…Moreover,t his ordered nanostructure is well-preserved with the variation of silver ion concentration and the amount of nanoconfined RIL (Supporting Information, Figures S14, S15). Similar to recent studies on ILs confined in carbon nanopores, [19] the nanoconfinement of RIL within BN nanochannels cripples the Coulomb force between cation and anion. Thei nteractions between RIL and BN favor the ordered alignment of cations and anions of RIL within BN nanochannels to create ac ontinuous silver distribution with high activity.A sar esult, the carrier-facilitated transport is enhanced significantly,leading to afast and selective ethylene transport.…”

Molecular Insights into the Regulatable Interfacial Property and Flow Behavior of Confined Ionic Liquids in Graphene Nanochannels

“…The SHAKE algorithm is also used to reduce high‐frequency vibrations of hydrogen in graphene oxide . In the simulations, the carbon atoms in the graphene sheet are fixed to maintain the planar structure of the sheet considering 2D sheet staked in a thin film case in the paper‐like membrane . The oxygen functional groups and ILs are kept at the temperature of 300 K using the Berendsen thermostat, with the temperature calculated after removing the center‐of‐mass velocity.…”

“…In the practical application scenario, ILs always combined with other nanoparticles or 2D materials to realize some specific functions such as a high capacity electrode, high selectivity gas separation membrane, safe immobilized catalyst, and so on. The nanoparticles can provide various nanoscale pores and 2D sheets may assemble in paper‐like structures with substantial nanochannels.…”