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

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.