Advances in 2D Transition Metal Dichalcogenide-Based Gas Sensors

Two-dimensional (2D) transition metal dichalcogenides (TMDs), such as MoS₂, MoSe₂, MoTe₂, WS₂, TaS₂, and VS₂ have emerged as highly promising candidates for next-generation gas sensors due to their unique electrical, chemical, and mechanical properties. Their high surface-to-volume ratio, tunable bandgaps, and ability to operate at room temperature make them particularly attractive for low-power, highly sensitive, and selective detection of toxic gases such as NO₂, NH₃, CO, and H₂S. These characteristics are especially relevant for modern applications in flexible and wearable electronics, where sensors must be compact, efficient, and compatible with Internet of things (IoT) technologies. This review critically examines recent advancements in TMD-based gas sensors, with a focus on synthesis strategies (e.g., chemical vapor deposition, exfoliation, and hydrothermal methods), sensing mechanisms, and performance metrics including sensitivity, selectivity, and response/recovery times. Furthermore, we discuss enhancement techniques such as defect engineering, doping, heterostructuring, and surface functionalization to improve sensor performance. The review concludes with an outlook on the key challenges and future directions for integrating TMD-based sensors into scalable, energy-efficient, and commercially viable environmental monitoring systems.