The effect of substrate on enhancing the sensing properties of nitric oxide gas detection of MoS₂ thin film

In recent times, there have been numerous proposals for utilizing sensors as a first warning signal for detecting toxic and hazardous gases, providing crucial alerts in extreme conditions before they escalate beyond control. There is an enormous demand for gas sensors to monitor reactions in industries and vehicles, aiming to mitigate air pollution. Molybdenum disulfide (MoS₂) is a well-known two-dimensional (2D) transition metal dichalcogenide (TMD) material with outstanding gas sensing properties. In this study, MoS₂ NO (nitric oxide) gas sensors with silicon (Si) and nickel (Ni) substrates were modeled and then simulated using Computer Solution (COMSOL) Multiphysics to evaluate their displacement efficiency. The simulated sensor indicated maximum displacements of 9.22 × 10¹⁰ µm for Si and 5.02 × 10¹⁰ µm for Ni substrates, with a molecular weight of NO as 30 g. Additionally, thin films were made into crystal structures, and the surface roughness was assessed employing X-ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, the sensor's response to varying flow rates of NO gas at different temperatures was examined to assess the sensitivity of the MoS₂ thin films to NO gas. Comparatively, the MoS₂ thin film deposited on the Si substrate had the highest sensitivity at 145.21%. In comparison, the film on the Ni substrate showed the lowest sensitivity at 17%, particularly at a low temperature of 40° C. The study demonstrates the potential of MoS₂ thin films as gas-sensing materials and emphasizes the importance of substrate selection in optimizing gas sensor performance for a variety of applications, including environmental monitoring and industrial processes.