Adsorption of H2S molecules on non-carbonic and decorated carbonic graphenes: A van der Waals density functional study

The adsorption of hydrogen sulfide (H2S) molecules on non-carbonic (B, Al, and Ga nitride) graphene was studied using a first-principles van der Waals density functional (vdW-DF) method. For the adsorption of a single molecule, we determined the most stable configurations, equilibrium geometries, adsorption energies, and electronic properties by approaching the molecule on the surface of non-carbonic graphenes at different possible sites. The Ga nitride (GaN) graphene was more capable of H2S molecule adsorption than the other graphenes due to the higher binding energy value and shorter bonding distance between the H2S molecule and the graphene surface. Electron transfer calculations confirmed that the electronic properties of GaN graphene changes significantly compared to other graphenes after H2S molecule adsorption. The density of states results indicated a stronger physical hybridization between H2S and GaN graphene. Furthermore, co-adsorption of two H2S molecules on the GaN graphene as a single-layer/bi-layer of adsorbed molecules was examined. Finally, Al and Ga metal atoms decorated on carbonic graphene (Al- and Ga-cargraph) to investigate H2S adsorption. The adsorption of H2S on Al- and Ga-cargraph was weaker than that on the non-carbonic graphenes. Therefore, based on the obtained results, GaN graphene is promising for uses in gas sensor devices for detect H2S.