Highly sensitive and selective room-temperature nitrogen dioxide sensors based on porous graphene

Development of high-performance nitrogen dioxide sensors is extremely important not only for industrial applications but also for environmental monitoring and health protection. For practical applications, gas sensors with high sensitivity for low concentrations of nitrogen dioxide are desired. Here, a simple process to fabricate high-performance gas sensors based on porous reduced graphene oxide (PRGO) through a simple drop-casting technique is presented. The PRGO used as active sensing material is prepared through a scalable solution etching approach. This sensor exhibited a high sensitivity in the sub-0.5 ppm range with good selectivity and reversibility, as well as a low experimental detection limit of 20 ppb, which is much lower than the threshold exposure limit proposed by the National Ambient Air Quality Standard (53 ppb). Furthermore, it can be performed at room temperature without UV/IR light illumination or thermal assistance. This superior performance could be attributed to the high adsorption site density due to the edge sites of porous graphene. The relationship between the sensing performance and the microstructure or chemical composition of porous graphene were systematically investigated. This work paves the way for a facile tailoring of the sensor behavior as a function of graphene micromorphology.