Organic adsorbates have higher affinities to fluorographene than to graphene

The large surfaces of two-dimensional carbon-based materials, such as graphene and fluorographene,are exposed to analytes, impurities and other guest molecules, so an understanding of the strength andnature of the molecule–surface interaction is essential for their practical applications. Using inverse gaschromatography, we determined the isosteric adsorption enthalpies and entropies of six volatile organicmolecules (benzene, toluene, cyclohexane, n-hexane, 1,4-dioxane, and nitromethane) to graphene and graphite fluoride powders. The adsorption entropies of the molecules ranged from −17 to −34 cal/mol Kand the maximum adsorption-induced entropy loss occurred for nitromethane at the high-energy sites.The enthalpies of bulkier adsorbates were almost coverage-independent on both surfaces and rangedfrom −11 to −14 kcal/mol. Despite the fact that fluorographene has lower surface energy than grapheneand graphene represents an ideal surface for the pi–pi stacking, the adsorbates had lower adsorptionenthalpies to fluorographene than to graphene by ∼9%. These findings imply that bulkier airbone organiccontaminants readily adsorb to the investigated surfaces and can modify the measured surface properties.