Diversiform gas sensors based on two-dimensional nanomaterials

Two-dimensional (2D) nanomaterials have been widely used in gas sensing due to their large specific surface area, high surface reactivity, and excellent gas adsorption properties. This paper reviews the typical synthesis methods of various types of 2D nanomaterials and summarizes the recent progress in gas sensors based on 2D materials, such as noble metal nanoparticles (NPs), metal oxides (MOS), conductive polymers, other new 2D materials. The methods of doping, modification, and photoexcitation can effectively improve the gas-sensing properties of 2D materials. The sensitive mechanisms of heterojunction, Schottky junction, and photoexcitation in 2D material sensors are discussed in detail. This paper discusses the application prospects of 2D materials in wearable gas sensors, food safety, and self-powered sensing, and provides ideas for further applications in environmental quality monitoring and disease diagnosis. In addition, the opportunities and challenges for gas sensors based on 2D materials are also discussed.