A Facile Approach to Fabricate QCM Humidity Sensor Based on Molybdenum Disulfide/Cellulose Nanocrystal Thin Film

In this article, molybdenum disulfide (MoS ₂ )/cellulose nanocrystal (CNC) nanocomposites are coated on silver electrodes of the quartz crystal microbalance (QCM) by the drop-coating method for humidity sensing. The performance of QCM humidity sensors of MoS ₂ , CNC, and MoS ₂ /CNC thin films is investigated in the relative humidity (RH) range of 11.31%–97.59%. The experimental results reveal that MoS ₂ /CNC humidity sensor has high sensitivity (ca. 36.03 Hz/%RH), which is higher than CNC (ca. 1.25 times) and MoS ₂ (ca. 2.5 times). Meanwhile, the sensor has excellent repeatability, high stability, and low humidity hysteresis (ca. 3.3%RH). Moreover, the Langmuir isotherm adsorption model is also used to investigate the humidity-sensitive mechanism of MoS ₂ /CNC humidity sensors. In addition, MoS ₂ /CNC humidity sensor can be well applicable for respiration monitoring which has good application prospect.