Atomic defects of graphene-carbon nanotubes impact on surface wettability

This paper aims to establish the relationship between defects in carbon nanotubes (CNT) grown on foam-like three-dimensional graphene (3DG) substrate (CNT/3DG) and its surface wetting property for developing a superhydrophobic surface. Both CNT and 3DG are grown by chemical vapor deposition. The defects in the CNT/3DG heterostructure are monitored using Raman and X-ray photoelectron spectroscopies as a function of graphene layers. A near superhydrophobic surface (-150 degrees) is identified by controlling the number of 3DG layers, which with subsequent encapsulation using polymethylmethacrylate/polypyrrole (PMMA/Ppy) polymer matrix presented a superhydrophobic surface with high structural integrity and stability. The usefulness of the superhydrophobic surface hereby developed, both in terms of adsorption performance of the surface and its reusability, has been evaluated for oil absorption performance from the water-oil mixture. Finally, the superhydrophobicity of the G-CNT-PMMA/PPy surface has been shown to result from its increased solid fraction from binary scanning electron microscopic images. These developments, i.e., correlating the defects in the nanotubes with surface wetting and subsequent polymeric modification in defect-controlled nanotubes to allow superhydrophobicity, provide numerous opportunities for designing suitable absorbents for water remediation.