First-Principles Predictions of MoS 2 -WS 2 In-Plane Heterostructures for Sensing Dissolved Gas Species in Oil-Immersed Transformers.

This work from first-principles insight uses a MoS 2 -WS 2 in-plane heterostructure as a potential sensing material for detection of CO and C 2 H 2 , two typical dissolved gases in oil-immersed transformers, in order to evaluate the operation status. The adsorption performance of the MoS 2 -WS 2 heterostructure upon two gas species is assessed via three adsorption sites and compared with isolated MoS 2 and WS 2 . Results indicate that MoS 2 -WS 2 performs with a much stronger binding force and charge-transfer for adsorptions of CO and C 2 H 2 in comparison to the isolated counterpart, which gives rise to more obvious deformation in the electronic property of MoS 2 -WS 2 as well as a much larger resistance-based sensing response. The recovery time of MoS 2 -WS 2 for desorption of CO and C 2 H 2 molecules is also appropriate to allow the reusability of such a sensor. The findings in this work uncover the admirable sensing potential of transition metal dichalcogenides (TMDs)-based heterostructures upon oil dissolved gases, which opens up a new way to explore novel 2D nanomaterials as resistive gas sensors for dissolved gas analysis in electrical oil-immersed transformers.