Development of accurate potentials for the physisorption of water on graphene

What is it about?

The specific honeycomb structure of graphene makes this material and its derivatives possible substrates to be used in technological processes as, for example, separation or storage of gases. To that end, the simplest way is to adsorb the gases on the graphene sheet. An important gas to be considered is water vapor, since it is present in a variety of post- and pre-combustion processes and, moreover, is an important greenhouse gas. The atomistic characterization of that kind of processes is often done by means of Molecular Dynamics simulations, which describe the movement of the atoms in a classical manner by using potentials (force fields) built up either empirically or theoretically. Our goal in this work is to design accurate potentials, keeping them as simple as possible, derived from high-quality quantum chemistry calculations, so to be able to adequately model the physisorption of water on graphene.

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Photo by Sam Balye on Unsplash

Photo by Sam Balye on Unsplash

Why is it important?

Recent studies employing different high-quality theoretical methods agree that the water-graphene interaction strength is weaker and less directional than previously thought. Consequently, one can expect that the description of the graphene surface and its properties are also different than predicted before. Thus, new potentials are required in order to reproduce the new ab initio data and to allow MD simulations that match those new findings on the physisorption of water on graphene in a computationally efficient way. To validate the novel potentials, the interaction energies between two water molecules and between water and circumcoronene or graphene are calculated both with the developed force fields and reference quantum chemical methods. The reliability of the new potentials is proven by their ability to mimic the CCSD(T) – the gold-standard in quantum chemistry– energy surface for interaction between the two water molecules. In the case of water–graphene interaction, also the results from the potential are almost coincident with those from high-level Quantum Chemistry methods.

Perspectives