Liquid Shear Exfoliation of MoS₂: Preparation, Characterization, and NO₂-Sensing Properties

2D materials possess great potential to serve as gas-sensing materials due to their large, specific surface areas and strong surface activities. Among this family, transition metal chalcogenide materials exhibit different properties and are promising candidates for a wide range of applications, including sensors, photodetectors, energy conversion, and energy storage. Herein, a high-shear mixing method has been used to produce multilayered MoS₂ nanosheet dispersions. MoS₂ thin films were manufactured by vacuum-assisted filtration. The structural morphology of MoS₂ was studied using ς-potential, UV-visible, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). The spectroscopic and microscopic analyses confirm the formation of a high-crystalline MoS₂ thin film with good inter-sheet connectivity and relative thickness uniformity. The thickness of the MoS₂ layer is measured to be approximately 250 nm, with a nanosheet size of 120 nm ± 40 nm and a number of layers between 6 and 9 layers. Moreover, the electrical characteristics clearly showed that the MoS₂ thin film exhibits good conductivity and a linear I-V curve response, indicating good ohmic contact between the MoS₂ film and the electrodes. As an example of applicability, we fabricated chemiresistive sensor devices with a MoS₂ film as a sensing layer. The performance of the MoS₂-chemiresistive sensor for NO₂ was assessed by being exposed to different concentrations of NO₂ (1 ppm to 10 ppm). This sensor shows a sensibility to low concentrations of 1 ppm, with a response time of 114 s and a recovery time of 420 s. The effect of thin-film thickness and operating temperatures on sensor response was studied. The results show that thinner film exhibits a higher response to NO₂; the response decreases as the working temperature increases.