An overview on room-temperature chemiresistor gas sensors based on 2D materials: Research status and challenge

It is necessary to develop efficient sensing materials, high-performance sensors and detailed mechanism study of chemiresistor gas sensors for applications in the fields of toxic gas monitoring, smart home, non-traumatic disease marker, wearable electronics, etc. Two-dimensional materials (2DMs), including graphene, transition metal dichalcogenides (TMDs), black phosphorus (BP), graphitic carbon nitride (g-C3N4), MXenes, metal-organic frameworks (MOFs), boron nitride (BN) and others, have proven to be attractive for fabrication of chemiresistor gas sensors due to their unique structure and remarkable characteristics. A major focus of this paper on advances and challenges in gas sensors based on 2DMs. Firstly, the electronic structure, physical and chemical properties and semiconductor properties of 2DMs are described. Secondly, the synthesis methods and gas-sensitive properties of 2DMs based gas sensors are introduced. In addition, strategies of improving gas sensors based on 2DMs are also discussed. Finally, the developments trend for 2DMs based gas sensors is presented from the following aspects: regulation of microstructure, contact between 2DMs and substrates, microelectromechanical systems (MEMS) based gas sensors and gas sensor arrays, flexible and wearable gas sensors, smart self-power and wireless gas sensors, theoretical calculation and in-situ characterization, influence of humidity on gas sensitivity.