Quasi-Unidirectional Transport Bilayer Two-Dimensional Nanopores for Highly-Efficient Molecular Sieving

Abstract

Two-dimensional nanopores are very promising for high-permeance molecular sieving, but the molecular backflow from permeate-side to feed-side is not beneficial for improving molecular permeance. We study the quasi-unidirectional molecular transport through a graphene-hexagonal boron nitride bilayer nanopore, aiming to realize a high-permeance molecular sieving. Molecular dynamics simulations of CO2/CH4 separations show that the bilayer pore presents 3.7 times higher selectivity comparing to the single-layer graphene nanopore with the same size. The quasi-unidirectional molecular transport is attributed to the distinctive adsorption abilities of gas molecules on the two sides of bilayer nanopores and the inhibited molecular backflow from permeate-side to feed-side. This work provides a promising way to realize the ultra-permeable porous membranes with molecular permeance even higher than the single-layer atomic-thickness membranes.

Advances in Two-Dimensional Ion-Selective Membranes: Bridging Nanoscale Insights to Industrial-Scale Salinity Gradient Energy Harvesting

“…The core components of NRED are ion-selective membranes, which play a crucial role in determining the overall process performance . Membrane performance relies on the subnano channel, which can be created either through the synthesis of porous materials from a bottom-up approach or by creating nanopores in nonporous materials from a top-down approach. − 2D porous materials with atomically precise structures offer advantages in the selective transportation of gas, water, and ions. − In SGE harvesting, the requirements of simultaneously improving ion selectivity and high conductivity have led to the development of 2D laminar and ultrathin membranes. These membranes are typically created by stacking nanosheets, resulting in interstitial interlayer spaces that function as nanofluidic channels.…”