“…For instance, previous studies reported that single and multi-layer MoS 2 and WS 2 field-effect transistor (FET) devices exhibit excellent sensitivity to a number of gas molecules, such as CO, CO 2 , NH 3 (5-50 ppm), NO and NO 2 (20 ppm) via changes in their resistivity induced by differences in their tendency to donate or accept charge from the substrates. [16][17][18][19][20][21][22][23] On the other hand, their extraordinary properties, such as high surface-to-volume ratio, free-carrier mobility, selective reactivity upon exposure to a range of analytes, rapid response and recovery make them a priority as gas sensors. Further, defects, doping elements, strain, and gate bias (electric field) are also important parameters to enhance the sensitivity and selectivity of a particular gas on TMDs.…”