▎ 摘　　要

Adsorption of caffeine and nicotine molecules on perfect, defective and porous graphene sheets is investigated using density functional theory. The high adsorption energies indicate strong adsorption of caffeine and nicotine molecules on graphene sheets. It was found that caffeine adsorption is stronger in comparison to nicotine adsorption. The electronic band structures analysis shows that the electronic properties of graphene sheets are sensitive to the presence of caffeine and nicotine molecules. The graphene sheets become n-type semiconductors with caffeine and nicotine adsorption. Our results suggest the possibility of using graphene based sensors for caffeine and nicotine detection. (C) 2016 Elsevier B.V. All rights reserved.