Characterization and room temperature ammonia sensing application of hydrothermally synthesized MoS2/RGO nanocomposites

Developing high-performance chemical gas sensor devices based on two-dimensional transition metal dichalcogenides (2D-TMDs) operating at room temperature is still a challenge due to the long and incomplete recovery. In this work, the hydrothermal technique was used to prepare molybdenum disulfide (MoS2)/reduced graphene oxide (RGO) nanocomposites at various amounts of graphene oxide (GO), and its effect on ammonia sensing has been investigated. For this, the weight percentage of GO to ammonium heptamolybdate tetrahydrate changed to 1 (MG1), 3 (MG3), 5 (MG5), and 10 (MG10). Raman analysis showed that the incorporation of GO causes the growth of the 1 T-MoS2 phase in nanocomposite samples. By examining the gas sensing properties of MoS2, RGO, and their nanocomposites, the optimal value of GO in MoS2 for the best performance of the sensor was achieved. The MG10 sample with the highest response (1.41 %), fastest response (58 s), and recovery (176 s) times under exposure to 500 ppm ammonia is the most suitable sensing material for fabricating ammonia sensors among other samples. This sample also showed excellent selectivity to ammonia compared to ethanol, methanol, and acetone. This study presents a new approach to exploit 2D nanocomposites for the detection of ammonia, as a biomarker in the human breath and also an important gas in industry.