Tuning the selective sensing properties of transition metal dichalcogenides (MoX2: X= Se, Te) toward sulfurrich gases

Abstract

<p>There is an urgent need for an efficient sensor to mitigate the effects of toxic pollutants possessing severe impacts on humans and the environment. Motivated by this, we investigated the selected transition metal dichalcogenides (MoX₂: X = Se, Te) monolayers toward the toxic sulfur-containing gases, such as H₂S and SO₂. We employed density functional theory simulations in combination with nonequilibrium Green's function formalism to study the optimized geometries, binding strength, electronic structures, charge transfer mechanism, and transport (current–voltage) characteristics of MoX₂ with and without H₂S and SO₂. Weak binding energies (<-0.30 eV) of H₂S/SO₂ on pristine MoX₂ were enhanced by selectively substituting the latter with elements like As, Ge, and Sb at lower doping concentrations of around 2%. We find that the doped MoX₂ strongly adsorbs H₂S/SO₂ yielding significant changes in their electronic properties, which were the fundamentals for the efficient sensing mechanism and were studied through the density of states and work function calculations. For the practical sensing applications, we considered the statistical thermodynamic analysis to investigate the sensing properties of pristine and doped MoX₂ monolayers under varied conditions of the temperatures and pressures. We are confident that our findings would pave the way for synthesizing sensitive and selective transition metal dichalcogenides-based nanosensor toward H₂S/SO₂.</p>