A review on 2D materials for surface acoustic wave gas sensors at room temperature

Surface acoustic wave (SAW) technology is widely used in communications and sensing applications. In SAW-based gas sensing applications, the sensitive material coated on the SAW sensor is critical for selectivity, limit of detection, and sensitivity, as it directly affects changes in sensing signals. Despite tremendous advances in this discipline, considerable hurdles remain in selecting suitable sensing materials, architectures, and mechanisms. Two-dimensional (2D) materials, including graphene and its derivatives, transition metal dichalcogenides, metal–organic frameworks, graphitic carbon nitride, and MXenes, show great promise for the development of SAW gas sensing devices. These 2D materials have peculiar properties such as high charge carrier mobility, numerous defects, dangling bonds, large surface area, and excellent mechanical flexibility. This study reviews current advances in 2D materials for SAW gas sensing applications, as well as the advantages of 2D materials and their derivatives for gas detection at room temperature. The purpose of this review paper is to provide an overview of current research and development on 2D materials-based SAW gas sensors, as well as to propose viable devices for a variety of room-temperature sensing applications. We elucidate the design, sensing mechanism, material selection, and performance of 2D material-based SAW gas sensors for detecting toxic and explosive gases such as NO₂, 2,4,6-trinitrotoluene, NH₃, H₂S, and dimethyl methylphosphonate, as well as humidity. Finally, we highlight the main challenges and potential solutions, as well as future directions for sensing materials used in SAW-based gas sensors.