Sensing of sulfur containing toxic gases with double transition metal carbide MXenes

Abstract

<p><p>Sensing of sulfur containing gases, such as hydrogen sulfide (H₂S) and sulfur dioxide (SO₂ ), on double transition metal carbide MXenes has been studied by means of density functional theory calculations. It is found that both H₂S and SO₂ strongly physisorbed on M₂ TiC₂T_x (M = Mo, Cr; T_x = O, S, OH) mono-layers. The adsorption of H₂S is stronger in the case of oxygen termination, (Mo₂TiC₂O₂, Cr₂TiC₂O₂), whereas SO₂ has stronger adsorption on sulfur terminated (Mo₂TiC₂S₂, Cr₂TiC₂S₂) monolayers. Binding characteristics of H₂S and SO₂ are further confirmed with Bader charge transfer, density of states, and charge density differences. Using a statistical thermodynamic analysis, the sensing mechanism of H₂S and SO₂ is studied under varied pressures and temperature conditions. By means of non-equilibrium Green's function calculations, the sensitivities of H₂S and SO₂ on the Mo₂TiC₂S₂ monolayer are found to be 16.3%, 10.3%, respectively, which showed promising sensing characteristics. Our results reveal that double transition metal carbide MXenes can be a potential candidate for the sensing of sulfur containing gases.</p></p>