A van der Waals density functional study of chloroform and bromoform on graphene

A calculational study of the trihalomethanes chloroform (CHCl_3) and bromoform (CHBr_3) adsorbed on graphene is presented. The study uses the van der Waals density functional method vdW-DF to obtain adsorption energies and adsorption structures for these molecules of environmental concern. In this study chloroform is found to adsorb with the H atom pointing away from graphene, with adsorption energy 357 meV (34.4 kJ/mol). For bromoform the calculated adsorption energy is 404 meV (39.0 kJ/mol). The corrugation of graphene as seen by chloroform is small, the difference in adsorption energy along the graphene plane is less than 6 meV.