Surface Engineering on Transition Metal Dichalcogenides: In Situ Encapsulation of Metal-Organic Frameworks for Highly Humidity-Resistant Gas Sensing at Room Temperature.

For their large specific surface areas and strong affinity with water molecules, two-dimensional (2D) material-based gas sensors are highly susceptible to the inference of ubiquitous relative humidity (RH) fluctuance, resulting in reduced accuracy and poor stability in real-world conditions. In this study, a metal-organic framework (MOF) encapsulation layer, 2D UiO-66-NH₂, was in situ constructed on the surface of molybdenum disulfide (MoS₂) via an aqueous synthesis method. Benefiting from the unique 2D UiO-66-NH₂ morphology formed on MoS₂ surface, the humidity-resistant nitrogen dioxide (NO₂) sensing performance of 2D UiO-66-NH₂/MoS₂ is dramatically enhanced within a wide RH range from 35% to 75% owing to the forceful suppression of the water molecules adsorption and condensation. It is worth mentioning that the selectivity of the material also improved as it is effectively shielded from interactions with water molecules and interfering gases. Furthermore, the practical limit of detection (LOD) for NO₂ of the sensor reaches an ultralow concentration of 20 ppb. The surface engineering strategy we demonstrated exhibits a significant advancement in the fabrication of high-performance, especially excellent humidity-resistant and selective 2D material-based gas sensors at room temperature.