Adsorption of thiophene and SOx molecules on Cr-doped and Ti-doped graphene nanosheets: a DFT study

Density functional theory calculations were carried out to investigate the structural and electronic properties of Cr- and Ti-embedded graphene monolayers. Sequentially, the adsorption of some gas molecules and thiophene molecule on these modified two-dimensional materials were examined in detail. The results suggest that the adsorption of all gas molecules on Cr- and Ti-embedded graphene monolayers is more energetically favorable than that on the pristine ones. Band structure calculations indicate that Cr-embedded graphene monolayer exhibits metallic behavior, while Ti-embedded one acts as a semiconductor. All the studied gas molecules were strongly adsorbed on the transition metal site of doped monolayer with the formation of covalent bonds. These strong chemical adsorptions were confirmed by the projected density of states and charge density difference plots. Charge density difference calculations also show that the electronic densities were mainly accumulated on the adsorbed gas molecules. The results presented in this study shed light on the prospective capability of transition metal decorated graphene nanosheets in sensing devices.