Preparation and mechanistic investigation of a flower-shaped MoSe2-SnS2 humidity sensor for respiratory monitoring

In this study, a nano-flower MoSe 2 -SnS 2 humidity sensor with S defects with fast response and low humidity hysteresis was prepared for respiratory and skin humidity detection. The increase in S vacancy defects provides more adsorption sites for water molecules and also facilitates the decomposition of water molecules and improves proton conduction. The construction of MoSe 2 -SnS 2 composite prompted an increase in the specific surface area of material exposing more active sites. This promoted the adsorption of water molecules on the device surface and accelerated the electron transfer between water molecules and the sensitive layer. The nanoflower structure of MoSe 2 -SnS 2 can provide channels for water molecules to be transported into the interior of material, which can effectively shorten the response time of sensor. MoSe 2 -SnS 2 sensor exhibited faster response/recovery time (13/15 s), lower humidity hysteresis (1%) and higher stability in the range of 11%-95% RH. In addition, MoSe 2 -SnS 2 humidity sensor can successfully detect respiration and skin moisture, showing the application potential of the sensor in the detection of respiration and skin humidity. This study provides a new idea for the preparation of high-performance 2D nano humidity sensors and promotes the expansion of new application areas for the sensors.