Room-temperature ppb-level NO2 sensor based on three-dimensional Mo2CTx nano-crumpled spheres

Achieving ppb-level nitrogen dioxide (NO 2 ) detection is of great significance in environmental monitoring and human daily life. The construction of portable and high-performance NO 2 sensor working at room temperature is the focus of attention. In this work, three-dimensional Mo 2 CT x nano-crumpled spheres (MS) sensitive material was designed and prepared via ultrasonic spray pyrolysis method, and a room-temperature planar type MS-based NO 2 sensor was successfully developed using drop-casting onto PI substrate with Au interdigital electrode. The sensor utilizing MS sensitive material exhibits the highest response value (−23.53%) to 5 ppm NO 2 and a lowest detection limit of 30 ppb at room temperature, also the excellent selectivity. Characterization and density functional theory calculation prove that the excellent NO 2 sensing properties are attributed to the increased specific surface area and more exposed edge-rich active sites which are caused by small size three-dimensional nano-crumpled spheres structure. This study provides a new strategy for improving the sensing performance of MXenes-based gas sensor and a new method for the construction of room temperature ppb-level NO 2 sensor.