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

Abstract

Achieving ppb-level nitrogen dioxide (NO2) detection is of great significance in environmental monitoring and human daily life. The construction of portable and high-performance NO2 sensor working at room temperature is the focus of attention. In this work, three-dimensional Mo2CTx nano-crumpled spheres (MS) sensitive material was designed and prepared via ultrasonic spray pyrolysis method, and a room-temperature planar type MS-based NO2 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 NO2 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 NO2 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 NO2 sensor.