Adsorption of common solvent molecules on graphene and MoS2 from first-principles

Abstract

Solvents are an essential element in the production and processing of two-dimensional (2D) materials. For example, the liquid-phase exfoliation of layered materials requires a solvent to prevent the resulting monolayers from re-aggregating, while solutions of functional atoms and molecules are routinely used to modify the properties of the layers. It is generally assumed that these solvents do not interact strongly with the layer and so their effects can be neglected. Yet experimental evidence has suggested that explicit atomic-scale interactions between the solvent and layered material may play a crucial role in exfoliation and cause unintended electronic changes in the layer. Little is known about the precise nature of the interaction between the solvent molecules and the 2D layer. Here, we use density functional theory calculations to determine the adsorption configuration and binding energy of a variety of common solvent molecules, both polar and non-polar, on two of the most popular 2D materials, namely, graphene and MoS. We show that these molecules are physisorbed on the surface with negligible charge transferred between them. We find that the adsorption strength of the different molecules is independent of the polar nature of the solvent. However, we show that the molecules induce a significant charge rearrangement at the interface after adsorption as a result of polar bonds in the molecule.

Composition dependence of the charge-driven phase transition in group-VI transition metal dichalcogenides

“…The optB86b-vdW exchange-correlation functional was used to account for long range dispersion interactions. 33,34 This functional was previously shown to give accurate lattice parameters and energies for layered materials 35,36 All calculations are performed with a cutoff energy of 500 eV for the plane wave basis set. A Γ centered K-point grid of 11×7×1 is used to calculate the total energy of the H and T phases, while a 11×5×1 grid is used for the T mixed phase.…”

Predicting biomolecule adsorption on MoS2 nanosheets with high structural fidelity

“…59,60 Notably, the adsorption energies provided in Table 1 have been systematically reported at reliable level of theory (vdW-DF2, as indicated by the benchmarking data, ESI † ). Adsorption energies of six of the organic compounds considered here were previously reported for different levels of theory (benzene, 24 toluene, 23 acetone, 61,62 ethane, 63,64 methanol, 61 and ethanol 62 ). As mentioned above, choice of a reliable level of theory is important in determination of the adsorption energy, and amongst the above previously reported data, only the adsorption energy of benzene 24 (45.4 kJ mol -1 ), which is in the same range of the reported value in the current work 47.1 kJ mol -1 , was determined with one of the benchmarked functionals (vDW-DF), and reported an adsorption structure comparable with that reported here.…”

“…[20][21][22] In addition, several attempts have sought to theoretically study the interactions between the MoS 2 surface and a wide range of compounds to shed light on these interfaces and explain experimentally observed properties. Density functional theory (DFT) has been used to study small-size adsorbates [23][24][25][26][27][28][29] in the gas phase environment because its capabilities to (usually) provide a solid understanding of the energetic behaviours and geometrical structures of adsorbates/analytes on surfaces. For more complicated and large-scale systems for which DFT approaches are not practical, molecular dynamics (MD) simulations, based on empirical inter-atomic potentials (force-fields), can be employed as a compromise between the rigour of the description and the relevance of the structural model.…”

Theoretical approach to point defects in a single transition metal dichalcogenide monolayer: conductance and force calculations in MoS 2

“…At first we consider pristine MoS 2 which is poorly reactive. In that respect, the molecular adsorption is driven by van der Waals interaction [53], and its inclusion in the calculations is of paramount importance. Unfortunately, this is not very convenient for designing electronic devices, as the molecules are very mobile in that configuration, with a high probability of diffusion with the temperature.…”