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

Abstract

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.

Solution-Processable and Printable Two-Dimensional Transition Metal Dichalcogenide Inks

“…After 8000 times bending, the gas detection performance remains nearly unchanged, showing potential in flexible and wearable electronic devices. Besides, the TMD materials were also hybridized with other layered crystals for use in NH 3 sensors. ,− For example, Zhang et al reported MoS 2 /VS 2 heterostructures, which demonstrate a higher NH 3 adsorption uptake than an individual MoS 2 or VS 2 sensor . You et al reported the Ti 3 C 2 T x /MoS 2 nanohybrids with Schottky heterojunctions for detecting a trace amount of NH 3 gas (e.g., 200 ppb) …”

The influence of advanced materials on the analytical performance of semiconductor-based gas sensors

“…These promising results lay the foundation for the development of next-generation gas sensors for diverse gas-sensing applications. 101…”