title: Enriching physisorption of H2S and NH3 gases on a graphane sheet by doping with Li adatoms.
abstract: We have used density functional theory to investigate the adsorption efficiency of a hydrogenated graphene (graphane) sheet for H2S and NH3 gases. We find that neither the pristine graphane sheet nor the sheet defected by removing a few surface H atoms have sufficient affinity for either H2S or NH3 gas molecules. However, a graphane sheet doped with Li adatoms shows a strong sensing affinity for both the mentioned gas molecules. We have calculated the absorption energies with one [referred to as half coverage] molecule and two molecules [referred to as full coverage] for both gases with the Li-doped graphane sheet. We find that for both the gases, the calculated absorption energies are adequate enough to decide that the Li-doped graphane sheet is suitable for sensing H2S and NH3 gases. The Li-doped sheet shows a higher affinity for the NH3 gas compared to the H2S gas molecules due to a stronger Li(s)-N(p) hybridization compared to that of Li(s)-S(p). However, while going from the half coverage effect to the full coverage effect, the calculated binding energies show a decreasing trend for both the gases. The calculated work function of the Li-doped graphane sheet decreases while bringing the gas molecules within its vicinity, which explains the affinity of the sheet towards both the gas molecules.
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Box 516, Uppsala University, S-75120, Uppsala, Sweden. tanveersaram@gmail.com tanveer.hussain@physics.uu.se puspamitra.panigrahi@physics.uu.se.
authors.forename: Tanveer
authors.initials: T
authors.lastname: Hussain
authors.forename: Puspamitra
authors.initials: P
authors.lastname: Panigrahi
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja