Preparation of MoS2 Nanospheres using a Hydrothermal Method and Their Application as Ammonia Gas Sensors Based on Delay Line Surface Acoustic Wave Devices

• Published in: Materials Vol. 16; no. 13; p. 4703
• Main Authors: Chung, Chan-Yu, Chen, Ying-Chung, Juang, Feng-Renn, Kao, Kuo-Sheng, Lee, En-I
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 29.06.2023; MDPI
• Subjects: Aluminum; Ammonia; Delay lines; Design; Electrodes; gas sensor; Gas sensors; Interdigital transducers; Lithium niobates; Magnetron sputtering; Molybdenum; Molybdenum disulfide; MoS2; nanosphere; Nanospheres; NH3; Outdoor air quality; Photolithography; Resonant frequencies; Room temperature; SAW; Sensitivity; Sensors; Substrates; Surface acoustic wave devices; Surface acoustic waves; Temperature; Thin films; United States > US; Japan
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16134703

An ammonia sensor based on a delay-line surface acoustic wave (SAW) device is developed in this study by coating the delay line area of the device with a nano-structured molybdenum disulfide (MoS2) sensitive material. A SAW device of 122 MHz was designed and fabricated with a pair of interdigital transducers (IDTs) defined on a 128° y-cut LiNbO3 substrate using photolithography technologies, and the aluminum IDT electrodes were deposited by a DC magnetron sputtering system. By adjusting the pH values of precursor solutions, molybdenum disulfide (MoS2) nanospheres were prepared with various structures using a hydrothermal method. Finally, an NH3 gas sensor with high sensitivity of 4878 Hz/ppm, operating at room temperature, was successfully obtained. The excellent sensitivity performance may be due to the efficient adsorption of NH3 gas molecules on the surfaces of the nanoflower-like MoS2, which has a larger specific surface area and provides more active sites, and results in a larger change in the resonant frequency of the device due to the mass loading effect.