Achievement of self-heated sensing of hazardous gases by WS (core)-SnO (shell) nanosheets.

With the recent rapid development of portable smart electronic devices, there is a great demand for gas sensors having high performance, high flexibility, and low energy consumption. We explored the effects of SnO shell thickness and operating voltage on the sensing behavior of WS nanosheets (NSs) deposited over a flexible substrate in self-heating mode. Commercial WS nanowires (NWs) were used as the core and SnO shells with various thicknesses were deposited on the core by an advanced physical technique, namely atomic layer deposition (ALD). With regard to CO sensing, a shell thickness of 15 nm operating at 3.4 V, was optimal. Alternatively, for NO sensing, the optimal shell thickness was 30 nm. Therefore, using engineering design principles to determine the shell material and shell thickness, it is possible to selectively detect reducing gases such as CO, while the response to oxidizing gases is weak. We have also discussed the details of this sensing mechanism. We believe that our results can lead to further study of C-S NSs for sensing studies from different points of views.