Adsorption of Water on Fluorinated Graphene

TL;DR

This study uses advanced DFT methods to analyze water adsorption on fluorinated graphene, revealing increased adsorption energies and altered water orientations compared to pristine graphene, with the most stable configuration above fluorinated carbon sites.

Contribution

It provides a comprehensive first-principles comparison of water adsorption on fluorinated versus pristine graphene using multiple DFT approaches.

Findings

Adsorption energies are significantly higher on fluorinated graphene.

Water dipole orientation is notably changed on fluorinated surface.

Most stable water configuration is above fluorinated carbon atoms.

Abstract

In this paper, we investigate the adsorption of water monomer on fluorinated graphene using state-of-the-art first principles methods within the framework of density functional theory (DFT). Four different methods are employed to describe the interactions between water and the carbon surface: The traditional DFT calculations within the generalized gradient approximation (GGA), and three types of calculations using respectively the semi-empirical DFT-D2method, the original van der Waals density functional (vdW-DF) method, and one of its variants. Compared with the adsorption on pristine graphene, the adsorption energies of water on fluorinated graphene are significantly increased, and the orientations of water diploe moment are notably changed. The most stable configuration is found to stay right above the top site of the C atom which is bonded with F, and the dipole moment of water molecule aligns spontaneously along the surface normal.