Jump to main content
Jump to site search

Issue 32, 2016
Previous Article Next Article

Stability of melamine-exfoliated graphene in aqueous media: quantum-mechanical insights at the nanoscale

Author affiliations

Abstract

In recent experiments, melamine (1,3,5-triazine-2,4,6-triamine) has been proposed as an effective exfoliating agent to obtain high quality graphene from graphite. After washing out the melamine in excess, small amounts (ppm) are still needed to stabilize the dispersion of graphene flakes in aqueous media. To understand the origin of this behaviour, we investigated the melamine–graphene–water system and the fundamental interactions that determine its structure and energetics. To disentangle the subtle interplay of hydrogen-bonding and dispersive forces we used state-of-the-art ab initio calculations based on density functional theory. First, we focused on the case of water molecules interacting with melamine–graphene assemblies at different melamine coverages. We found that water–melamine interactions provide the driving force for washing off the melamine from graphene. Then, we addressed the interaction of single and double layers of water molecules with the graphene surface in the presence of an adsorbed melamine molecule. We found that this melamine acts as a non-covalent anchor for keeping a number of water molecules conveniently close to the graphene surface, thus helping its stabilization in aqueous media. Our analysis helps understanding how competing weak forces can lead to a stable graphene water suspension thanks to small amounts of adsorbed melamine. From our results, we derive simple indications on how the water–graphene interfacial properties can be tuned via non-covalent adsorption of small functional molecules with H-bond donor/acceptor groups. These new hints can be helpful to prepare stable graphene dispersions in water and so to unlock graphene potential in aqueous environments.

Graphical abstract: Stability of melamine-exfoliated graphene in aqueous media: quantum-mechanical insights at the nanoscale

Back to tab navigation

Supplementary files

Publication details

The article was received on 16 Jun 2016, accepted on 13 Jul 2016 and first published on 13 Jul 2016


Article type: Paper
DOI: 10.1039/C6CP04213A
Phys. Chem. Chem. Phys., 2016,18, 22203-22209

  •   Request permissions

    Stability of melamine-exfoliated graphene in aqueous media: quantum-mechanical insights at the nanoscale

    A. M. Rodríguez, A. B. Muñoz-García, O. Crescenzi, E. Vázquez and M. Pavone, Phys. Chem. Chem. Phys., 2016, 18, 22203
    DOI: 10.1039/C6CP04213A

Search articles by author

Spotlight

Advertisements