First principles analysis of graphene and its ability to maintain long-ranged interaction with H2S

We determine the chemical activity of (a) carbon site of pristine graphene, (b) Stone–Wales (SW) defect site, and (c) BN-sites of BN-doped graphene towards adsorption of a toxic gas H2S, through comparative analysis based on first-principles density functional theoretical calculations incorporating van der Waals (vdW) interactions. While the adsorption of H2S is weak at both C and BN sites with a binding energy of 15kJ/mol, it is significantly stronger at the Stone–Wales defect site with a much higher binding energy of 26kJ/mol. This is clearly reflected in the contrasting orientation of H2S molecule in the relaxed geometries: the sulfur atom of H2S is closer to graphene (at a distance 3.14Å) during physisorption at C and BN sites, while the molecule's H atoms come closer to graphene (at a distance 2.84Å) during physisorption at the Stone–Wales defect site. The origin of the stronger binding interaction between H2S and a SW defect site is attributed to two possible reasons: (i) an increase in the vdW interaction; and (ii) the lowering of both energy of the HOMO level and the total energy of the H2S molecule in attaining a stable configuration. Our findings are compared to the available theoretical results and their technological relevance is further discussed. •Interactions of H2S with defected and doped graphene studied via first principles.•H2S has a van der Waals (vdW) interaction with all graphene systems.•Stone-Wales defect has the strongest vdW interaction with large electric dipoles.•Defected Graphene should be more suitable for gas storage of H2S gas.