Two-dimensional MoSe nanosheets via liquid-phase exfoliation for high-performance room temperature NO gas sensors.

Molybdenum selenide (MoSe) has drawn significant interest due to its typical semiconductor properties. MoSe is a relatively novel material in the field of gas sensors especially at room temperature. Herein, we utilize a facile and efficient synthetic method of liquid-phase exfoliation to exfoliate bulk MoSe into nanosheets. Anhydrous ethanol is used as dispersant, so the low boiling point makes it easy to be removed from MoSe nanosheets, which does not affect the subsequent sensing performance. The exfoliated few-layered MoSe nanosheets shows significantly enhanced NO gas response (1500% to 10 ppm NO which is 18 times greater than pristine bulk MoSe), a low detection concentration (50 ppb), an outstanding repeatability, a remarkable selectivity, and a reliable long-term device durability (more than 60 d) at room temperature (25 °C). The reason of the significant improvement in gas sensing performance can be attributed mainly to the higher surface-to-volume ratio of exfoliated MoSe nanosheets. It promotes the adsorption of gas molecules on the surface of the material, thereby facilitating the charge transfer process. The superior performance of this gas sensor makes MoSe nanosheets a potential candidate for room temperature NO detection.