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

Few-layer MoS2 with exceptionalphysical andchemicalproperties has attracted notable attention for next-generation gassensors. The layer-dependent sensing performance for detecting NO2 based on MoS2 is not fully understood. Here, wereport the direct synthesis of high-crystallinity uniform few-layerMoS(2) via chemical vapor deposition. The influence of layerthickness 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 roomtemperature. Further density functional theory calculations revealthat the bilayer MoS2 with an AA stacking sequence is morefavorable for the physisorption of NO2 molecules due tothe more negative adsorption energy, facilitating charge transferduring the NO2 adsorption and thus increasing the electricalresponse of the gas sensors. This work provides a basic understandingof layer-dependent gas-sensing performance and serves as a referencefor designing room-temperature gas sensors for low power consumptionand reliable responsivity.