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

Abstract

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.