Adsorption of Ethanol, Water, and Ethanol–Water Dimers on Open-Ended Graphene Capillaries Studied by Ab Initio Methods: Unraveling the Ethanol and Water Attachment at the Edges

Thisab initio study evaluated the interaction of ethanol, water,and ethanol-water dimers with an open-ended graphene capillary(GC). The results for a 10 & ANGS; GC showed that the ethanol stabilityon the surface depends on the molecule orientation within the structureand its position along the GC cross-section. The vertically orientedadsorbed ethanol finds the most stable site at the GC edges. However,when the ethanol lies on the surface, it is more stable at the GCcenter. In contrast, the water molecules are more stable at the GCedge. The analysis shows that the vertically aligned molecule presentsa stronger ethanol-GC bond at the edge, with enhanced covalentcharacteristics. This holds for GCs with different widths but is modifiedas a function of the interlayer separation (d). For d larger than & SIM;12 & ANGS; the ethanol laying on theGC center becomes favorable, as well as the vertically oriented moleculelaying on the surface at & SIM;7 & ANGS;. As single molecules, ethanoland water receive charges, but upon dimer formation, ethanol donatesand water gains. Interestingly, the ethanol-GC covalent bondenhances while it decreases for water-GC in the dimer, comparedto the single molecule adsorption. These results clarify the ethanol-water/GCinteraction.