Adsorption and diffusion of water on graphene from first principles

Water monomer adsorption on graphene is examined with state-of-the-art electronic structure approaches. The adsorption energy determinations on this system from quantum Monte Carlo and the random-phase approximation yield small values of <100 meV. These benchmarks provide a deeper understanding of the reactivity of graphene that may underpin the development of improved more approximate methods enabling the accurate treatment of more complex processes at wet-carbon interfaces. As an example, we show how dispersion-corrected density functional theory, which we show gives a satisfactory description of this adsorption system, predicts that water undergoes ultra-fast diffusion on graphene at low temperatures.

Figure 1

Water adsorption structures considered. (a) The two-leg structure shown from the side (top) and from above (bottom). (b) The one-leg structure shown from the side (top) and from above (bottom). For clarity only a small part of the periodic simulation cell is shown.

Figure 2

Adsorption energy versus O atom height for water on graphene obtained with various methods. (a) and (c) The two-leg configuration. (b) and (d) The one-leg configuration. In the upper panels, DMC and RPA are compared. In the lower panels, RPA and the various $\mathit{xc}$ functionals are compared.