Layer-Dependent NO2‑Sensing Performance in MoS2 for Room-Temperature Monitoring.

Few-layer MoS₂ with exceptional physical and chemical properties has attracted notable attention for next-generation gas sensors. The layer-dependent sensing performance for detecting NO₂ based on MoS₂ is not fully understood. Here, we report the direct synthesis of high-crystallinity uniform few-layer MoS₂ via chemical vapor deposition. The influence of layer thickness on the NO₂-sensing performance is evaluated. We show that, as compared to the monolayer and trilayer counterparts, the bilayer MoS₂ presents the best sensitivity at room temperature. Further density functional theory calculations reveal that the bilayer MoS₂ with an AA stacking sequence is more favorable for the physisorption of NO₂ molecules due to the more negative adsorption energy, facilitating charge transfer during the NO₂ adsorption and thus increasing the electrical response of the gas sensors. This work provides a basic understanding of layer-dependent gas-sensing performance and serves as a reference for designing room-temperature gas sensors for low power consumption and reliable responsivity. [ABSTRACT FROM AUTHOR]