First-Principles Study of the Interactions between Graphene Oxide and Amine-Functionalized Carbon Nanotube

Abstract

We applied plane-wave density functional theory to study the effects of chemical functionalizations of graphene and carbon nanotube (CNT) on the properties of graphene–CNT complexes. The functionalizations of graphene and CNT were modeled by covalently attaching oxygen-containing groups and amines (NH2), respectively, to the surfaces of these carbon nanomaterials. Our results show that both dispersion energy and hydrogen bonding play crucial roles in the formation of complexes between graphene oxide (GO) and CNT–NH2. At a lesser degree of functionalization, the interaction energies between functionalized graphene and CNT were either unchanged or decreased, with respect to those without functionalization. Our study indicated that the gain or loss of interaction energy between graphene and CNT is a competition between two contributions: dispersion energy and hydrogen bonds. It was found that the heavy functionalization of graphene and CNT could be a promising route for enhancing the interaction energy between them. Specifically, the carboxyl-functionalized GO produced the greatest increase in the hydrogen bond strength relative to the dispersion energy loss. The influence of Stone–Wales defects in CNT on the computed interaction energies was also examined. The computed electron density difference maps revealed that the enhancement in the interaction energy is due to the formation of several hydrogen bonds between oxygen-containing groups of GO and NH2-groups of CNT. Our results show that Young’s moduli of carbon nanomaterials decrease with the increasing concentration of functional groups. The moduli of GO–CNT–NH2 complexes were found to be the averages of the moduli of their constituents.

Role of Stone-Wales defects on the interfacial interactions among graphene, carbon nanotubes, and Nylon 6: A first-principles study

“…Because of the relatively large system size (containing up to 259 atoms), only the Γ-point (k = 0) of the Brillouin zone was sampled. 43,44 Furthermore, the convergence test with respect to the k-point sampling (1 × 1 × 1 vs 3 × 3 × 1 k-points tested) confirmed that Γpoint sampling was sufficient to achieve the convergence of computed interaction energy within 0.02 eV/nm. In addition, denser k-point grids were used for the calculations of electronic DOS.…”

“…This approach of combining the vdW-DF2 functional with the pseudopotentials designed for the PBE functional has been successfully employed in several previous studies. [40][41][42][43] To validate our computational approach, we first calculated the structures of pristine CNT, graphene, and the CNT + graphene complex and compared them with the available results (described in Sec. III A).…”

“…All the computed interaction energies were normalized by the length of the CNT (the cell dimension along the x-direction). 15,43…”

Dependence of the Properties of 2D Nanocomposites Generated by Covalent Crosslinking of Nanosheets on the Interlayer Separation: A Combined Experimental and Theoretical Study

“…The interaction energy ( E int ) of the composites is defined as [Eq. ]: …”

Ovalbumin-mediated synthesis and simultaneous functionalization of graphene with increased protein stability

“…The FTIR spectrum of graphene oxide shows the presence of sharp bands at 1734 cm −1 (for C=O stretching), 1620 cm −1 (for C=C stretching), 1224 cm −1 (for C-O-C stretching), 1054 cm −1 (for C-O stretching), and 3421 and 1385 cm −1 for hydroxyl group deformation peak. These band positions indicate the presence of oxygen containing moieties such as carbonyl, carboxylic, epoxy, and hydroxyl in graphene oxide (31,32). The FTIR spectrum of ovalbumin reduced graphene shows a drastic decrease in intensities of all oxygen functionalities peaks at 1734, 3421, and 1385 cm −1 , which corresponds to C=O stretching and OH deformation vibration, respectively.…”