Adsorbing H2S onto a single graphene sheet: A possible gas sensor

The electronic structure of pristine graphene sheet and the resulting structure of adsorbing a single molecule of H2S on pristine graphene in three different sites (bridge, top, and hollow) are studied using the full potential linearized augmented plane wave method. Our calculations show that the adsorption of H2S molecule on the bridge site opens up a small direct energy gap of about 0.1 eV at symmetry point M, while adsorption of H2S on top site opens a gap of 0.3 eV around the symmetry point K. We find that adsorbed H2S onto the hollow site of pristine graphene sheet causes to push the conduction band minimum and the valence band maximum towards Fermi level resulting in a metallic behavior. Comparing the angular momentum decomposition of the atoms projected electronic density of states of pristine graphene sheet with that of H2S–graphene for three different cases, we find a significant influence of the location of the H2S molecule on the electronic properties especially the strong hybridization between...