Selective Dibenzothiophene Adsorption on Graphene Prepared Using Different Methods

Graphite oxide synthesized with phosphoric acid, labeled “GOP”, shows a higher degree of oxidation and has a larger interlayer spacing than the oxide prepared using the conventional Hummers method, referred to as “GOH”, as confirmed by X-ray photoelectron spectroscopy and X-ray diffraction analyses. This study was performed under the assumption that the oxygen-containing functional groups between the GOP layers are more easily reduced than those between the GOH layers. Raman analysis supported this assumption in that the reduced graphene from GOP has a larger number of sp2 carbons and fewer defects than the graphene obtained from GOH. The relative extent of defects in graphene can be investigated by dibenzothiophene (DBT) adsorption, which requires π–π interactions between the free π-bonds of sp2 atoms from graphene and those from the aromatic ring of DBT. The graphene obtained from GOP showed higher DBT adsorption capacity than that synthesized from GOH. In addition, the DBT adsorption capacity on graphene decreased as the concentrations of other aromatic compounds increased.