The adsorption enhancement of graphene for fluorine and chlorine from water

Abstract A high concentration of F (Cl) element in drinking water threatens people’s health. Hence, in this work, we systematically investigated the F and Cl atoms adsorption on pristine graphene (PG) or defective graphene (vacancy and Al, B, Si-doped) by using density functional theory calculations to explore materials with stronger adsorption performance for F and Cl elements removal from water. Based on the analysis of adsorption energy, PDOS and charge population, results indicate that F/Cl atom preferentially adsorbed on the Top site of graphene. We also find that the vacant graphene and doped graphene are good candidates for the adsorbents for F and Cl atom because the single F or Cl atom can be strongly trapped in the positions of defects. The negative adsorption energy and the diffusion barrier suggest that the F/Cl-AlG system has the most thermodynamic stability among our considered systems. In the H2O environment, the adsorption energy for the co-adsorption of F(Cl) atom and H2O molecule on Al-doped graphene is −4.2 eV(−3.77 eV), suggesting that the strong adsorption performance still presents between F(Cl) atom and Al-doped graphene in a background of H2O molecule.