Thermodynamics of Adsorption on Graphenic Surfaces from Aqueous Solution.

Adsorption of organic molecules from aqueous solution to the surface of carbon nanotubes or graphene is an important process in many applications of these materials. Here we use molecular dynamics simulation, supplemented by analytical chemistry, to explore in detail the adsorption thermodynamics of a diverse set of aromatic compounds on graphenic materials, elucidating the effects of the solvent, surface coverage, surface curvature, defects, and functionalization by hydroxy groups. We decompose the adsorption free energies into entropic and enthalpic components and find that different classes of compounds-such as phenols, benzoates, and alkylbenzenes-can easily be distinguished by the relative contributions of entropy and enthalpy to their adsorption free energies.