Unveiling the Chemical Underpinnings behind the Enhanced Adsorption Interaction of NO 2 on MoS 2 , MoSe 2 , and MoTe 2 Transition Metal Dichalcogenides

The demand for efficient gas sensors has fueled research into novel materials such as transition-metal dichalcogenide (TMD) compounds. TMDs such as MoS2, MoSe2, and MoTe2 have shown promise in detecting NO2. However, it remains uncertain which one is best suited for this purpose. Consequently, this study employs computational methods to investigate the adsorption of NO2 on monolayers of MoS2, MoSe2, and MoTe2. The results show that MoTe2 exhibits the strongest interaction with the highest charge transfer, suggesting its potential for superior NO2 detection compared to MoSe2 and MoS2. The sheets share the same type of outward-projecting orbitals, and thus, they also share the principal mode of charge projection. However, the bonding within the sheet influences the accumulation of charge within it, which in turn impacts the availability of electrons on its surface. Subsequently, the mechanism of charge transfer between the TMDs and NO2 remains the same, but more available charge results in an enhanced adsorption interaction. The described mechanism is likely to affect the adsorption of other acceptor-type molecules (e.g., CO2, SO2, H2S, or BF3) and also be behind differences in charge transfer observed among group VI compounds (e.g., MoS2 and WS2).