Insight into mechanism of temperature-dependent limit of NO₂ detection using monolayer MoS₂

Recently, many literatures report on the excellent performance of MoS₂-based NO₂ sensing, however, lacking the study on its thermal stability. Here, the insight mechanism in NO₂ sensor reactivity of monolayer MoS₂ at different temperatures from 25 to 200 °C was investigated. The relative effect of the morphological properties of the sensor and gas sensor reactivity at different temperatures was observed using in situ Raman mapping, optical microscope, and scanning electron microscope to demonstrate the mechanism of temperature-dependent limit of NO₂ detection in ppb. By increasing the temperature from 25 to 100 °C, the response of the sensor significantly improves (4.8 % vs. 54.4 %) at 200 ppb, and its limit of NO₂ detection strongly decreases (48.0 vs. 6.9 ppb). Interestingly, the sensor performance from 100 to 150 °C is likely equivalent to a limit of detection (LoD) that varies from 8.1 to 6.9 ppb, and the LoD slightly increases to 15.0 ppb at 200 °C. The line damages were found in monolayer MoS₂ basal plane by heating the sample up to 200 °C, that affect to the recovery of the NO₂ sensor. This study reveals an effective approach that may be useful in developing a gas sensor with a high response and limit of NO₂ detection in the ppb scale.