Detection of DMF and NH₃ at Room Temperature Using a Sensor Based on a MoS₂/Single-Walled Carbon Nanotube Composite

Two-dimensional molybdenum disulfide (MoS2) with highsurface area and layered structure has received substantial attentionfor its potential use in detecting volatile organic compounds (VOCs)and trace gases with good relative response and selectivity at roomtemperature. However, two of the long-standing challenges to broaderuse of MoS2 are its poor recovery kinetics and susceptibilityto oxidation in a humid environment. To address these issues, we presenta chemiresistive sensor based on a MoS2/SWCNTs compositeas a sensing material for the dual detection of N,N-dimethylformamide (DMF) and ammonia (NH3) at room temperature. MoS2 supports SWCNTs by providinga superhydrophobic surface and imparting environmental stability alongwith an increased specific surface area. The composite-based sensorwith 4 wt % SWCNTs enabled dual detection of DMF and NH3 down to 0.1 and 1 ppm, respectively, under ambient conditions. Uponexposure to 5 ppm DMF (response approximate to 15%), this sensor exhibitedp-type conduction with response and recovery times of 160 and 140s, respectively, whereas, with 5 ppm of NH3 (response approximate to 25%,n-type), these times were 126 and 35 s, respectively. Moreover, thecomposite sensor exhibited high selectivity against various oxidizingand reducing agents as well as good repeatability, long-term stability,and fast reversibility in varied gas atmospheres. We attribute thisenhanced sensing performance to the formation of numerous p-ninterfaces and synergy between the two nanomaterials. This improvescharge transport and leads to a faster response. The experimentalwork was supplemented by a machine learning-based principal componentanalysis (PCA) model, which enabled us to identify key dependent variablesand confirm the sensor's dual selectivity. These results providea platform for developing next-generation gas sensors for diversepotential gas-sensing applications.