Effect of functional groups on the adsorption of graphene oxide on iron oxide surface

Density functional theory (DFT) calculations are performed to explore the effect of functional groups (hydroxyl and epoxy groups) on the interfacial interaction of graphene oxide (GO) with iron oxide (Fe2O3) substrate. The calculation results indicate that the adsorbed functional groups can improve the interaction strength between GO and Fe2O3 substrate, and the magnitude of binding energy enhancement is associate with the adsorption sites of functional groups. For the GO/Fe2O3-O models with a neighboring C atom of the oxidized atom at the top of a surface O atom, the binding energy is significantly enhanced, which arises from the formation of interfacial C-O covalent bonds. Moreover, the maximum binding energy of GO/Fe2O3-O model is more than four times that of Gr/Fe2O3-O model. For the other GO/Fe2O3-O and GO/Fe2O3-Fe models studied in this work, the GO layer is physisorption on Fe2O3 surface and the binding energy enhances slightly. This study contributes to a deeper understanding of the protection properties of graphene-based coating materials on iron oxide surface.