Selective surface adsorption and pore trapping for ethanol-water mixtures near single-layer polyporous graphynes

The interfacial behavior of ethanol-water mixtures with various concentrations near single-layer polyporous gamma-graphyne (Graphyne-n, n=3,4,5) surfaces were investigated using molecular dynamics simulation. Comprehensive energetic analysis and structure properties, including density profiles, radial distribution functions, orientation distributions, and surface two-dimensional densities, have been simulated to quantify the surface-induced effect. Our simulation results illustrate micro-phase demixing phenomenon with ethanol molecules preferential adsorbing on the graphyne surfaces. This surface induced demixing behavior is enhanced as the pore area decreases for the gamma-graphynes, that is, G-3 surface induces the strongest demixing of ethanol-water mixture. Meanwhile, when in contacting with the graphyne-4 and graphyne-5 surfaces, ethanol molecules from the mixture are able to predominately occupy the nanopores of graphynes, and display selective ethanol penetration through single-layer graphynes. This unique interface behavior could be attributed to the enhanced hydrophobic interaction between amphiphilic ethanol molecules and graphyne carbon surfaces. (C) 2016 Elsevier B.V. All rights reserved.