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

Two-dimensional molybdenum disulfide (MoS 2 ) with high surface area and layered structure has received substantial attention for its potential use in detecting volatile organic compounds (VOCs) and trace gases with good relative response and selectivity at room temperature. However, two of the long-standing challenges to broader use of MoS 2 are its poor recovery kinetics and susceptibility to oxidation in a humid environment. To address these issues, we present a chemiresistive sensor based on a MoS 2 /SWCNTs composite as a sensing material for the dual detection of N, N -dimethylformamide (DMF) and ammonia (NH 3 ) at room temperature. MoS 2 supports SWCNTs by providing a superhydrophobic surface and imparting environmental stability along with an increased specific surface area. The composite-based sensor with 4 wt % SWCNTs enabled dual detection of DMF and NH 3 down to 0.1 and 1 ppm, respectively, under ambient conditions. Upon exposure to 5 ppm DMF (response ≈15%), this sensor exhibited p-type conduction with response and recovery times of 160 and 140 s, respectively, whereas, with 5 ppm of NH 3 (response ≈25%, n-type), these times were 126 and 35 s, respectively. Moreover, the composite sensor exhibited high selectivity against various oxidizing and reducing agents as well as good repeatability, long-term stability, and fast reversibility in varied gas atmospheres. We attribute this enhanced sensing performance to the formation of numerous p–n interfaces and synergy between the two nanomaterials. This improves charge transport and leads to a faster response. The experimental work was supplemented by a machine learning-based principal component analysis (PCA) model, which enabled us to identify key dependent variables and confirm the sensor’s dual selectivity. These results provide a platform for developing next-generation gas sensors for diverse potential gas-sensing applications.