Resistive gas sensors for the detection of NH₃gas based on 2D WS₂, WSe₂, MoS₂, and MoSe₂: a review

Transition metal dichalcogenides (TMDs) with a two-dimensional (2D) structure and semiconducting features are highly favorable for the production of NH₃gas sensors. Among the TMD family, WS₂, WSe₂, MoS₂, and MoSe₂exhibit high conductivity and a high surface area, along with high availability, reasons for which they are favored in gas-sensing studies. In this review, we have discussed the structure, synthesis, and NH₃sensing characteristics of pristine, decorated, doped, and composite-based WS₂, WSe₂, MoS₂, and MoSe₂gas sensors. Both experimental and theoretical studies are considered. Furthermore, both room temperature and higher temperature gas sensors are discussed. We also emphasized the gas-sensing mechanism. Thus, this review provides a reference for researchers working in the field of 2D TMD gas sensors.