Multiscale molecular simulations on interfacial adsorption and permeation of nanoporous graphynes

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.