Elemental Substitution of Two-Dimensional Transition Metal Dichalcogenides (MoSe₂ and MoTe₂): Implications for...

The quest for a suitable material with the potential of capturing toxic nitrogen-containing gases (NH₃, NO, and NO₂) has motivated us to explore the structural, electronic, and gas-sensing properties of transition metal dichalcogenides (TMDs); MoSe₂ and MoTe₂. Spin-polarized density functional theory (DFT) calculations demonstrate weak binding of nitrogen-containing gases (NCGs) with the pristine TMDs, which limits the use of the latter as efficient sensing materials. However, suitable elemental substitutions improve the binding mechanism enormously. Our dispersion-corrected DFT calculations revealed that Se (Te) substitution with Ge (Sb) in MoSe₂ (MoTe₂) not only enhances the binding energies but also causes a significant variation in the electronic properties and work functions. A charge-transfer mechanism based on Bader analysis indicates that transfer of charges from MoSe₂-Ge (MoTe₂-Sb) to the NCGs is responsible for the improvement in the binding characteristics. Based on our findings, it is evident that 2.08% of elemental substitutional makes both MoSe₂ and MoTe₂ promising materials for NH₃, NO, and NO₂ gas sensing.