A theoretical analysis of the role of defects in the adsorption of hydrogen sulfide on graphene

Density functional theory studies are reported to analyze the interaction between hydrogen sulfide (H2S) and graphene. The electron-ion interactions have been modeled using ultrasoft pseudopotentials and the exchange-correlation energies have been approximated by the method of the generalized gradient approximation in the parameterization of Perdew-Burke-Ernzerhof. Three graphene structures, one intrinsic and two with defects (vacancy and sustitution), and four H2S concentrations have been studied. The optimal geometries, binding energies, density of states (DOS) and charge density were obtained. In order to study the adsorption process three high symmetry sites were considered, namely, top, bridge, and center. The preferential adsorption structure corresponds to the center site in a physical way. The DOS of graphene-H2S systems shows a metallic behavior which coincides with the behavior of the isolated graphene. The geometrical structure of the graphene and the hydrogen sulfide remains unchanged.