Multiscale molecular simulations on interfacial adsorption and permeation of nanoporous graphynes

Abstract

Graphyne has been proposed as a distinctive molecular sieving membrane due to its intrinsic nanoscale pores and single-atom thickness. However, this novel application requires a precise quantification and understanding of the molecular interaction at graphyne interfaces, which can modulate molecular transport across graphyne. Herein, interfacial adsorption and permeation of ethanol–water mixtures on graphynes are studied by a multiscale simulation strategy, in which dispersion-corrected density functional theory (DFT-D) and classical molecular dynamics (MD) are combined. Our results show that graphyne possesses differential surface affinities with ethanol and water, provoking a preferential adsorption layer of ethanol. The adsorption on the graphyne surface is dominated by attractive dispersion force, even for polar water molecules. As a joint function of ethanol-rich segregation adsorption on graphyne and preferred pore occupation of ethanol, polyporous graphyne with a suitable pore size is envisioned to act as an alcohol-permselective membrane. Our simulation results present new insights into interfacial interaction and have an impact on the promising application of two-dimensional graphyne membranes.