Highly sensitive humidity sensor based on a composite of MoS₂ and multi-walled carbon nanotube sensing film

Abstract Humidity sensors are gaining more importance in daily life, industrial processes, weather forecasting, and medical monitoring. Hence, there is a constant quest to develop humidity-sensing materials that exhibit fast response/recovery time, good sensitivity, and long-term durability. In this paper, a fast and highly sensitive humidity sensor based on the composite of molybdenum disulfide (MoS 2 ) and multi-walled carbon nanotube (CNT) is demonstrated, and their performance is compared with pristine CNT based humidity sensor. The MoS 2 nanosheets were synthesized by a facile liquid exfoliation method. The structural analysis revealed the formation of MoS 2 nanosheets, their composite with multi-walled CNT (MoS 2 /CNT), and the presence of defects in MoS 2 /CNT composite. The defects act as active sites for the adsorption of water molecules. Therefore, the large surface-to-volume ratio and active sites in MoS 2 /CNT composite sensing film led to enhanced water adsorption even at low humidity regimes (<25%RH), while in the pristine CNT sensing film, the water adsorption enhanced at higher humidity regimes (>50%RH). The MoS 2 /CNT composite based humidity sensor showed a large average sensitivity of 9.016 MΩ/%RH and a fast response/recovery time of 2 s/5 s, which is much lower than the response/recovery time (10 s/36 s) of the pristine CNT based humidity sensor. Current findings indicate that MoS 2 /CNT composite materials could be a great choice for humidity sensors.