High-Performance Gas Sensor Using a Large-Area WS_{2 x}Se_{2-2 x} Alloy for Low-Power Operation Wearable Applications

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have attracted considerable attention as promising building blocks for a new generation of gas-sensing devices because of their excellent electrical properties, superior response, flexibility, and low-power consumption. Owing to their large surface-to-volume ratio, various 2D TMDCs, such as MoS₂, MoSe₂, WS₂, and WSe₂, have exhibited excellent gas-sensing characteristics. However, exploration toward the enhancement of TMDC gas-sensing performance has not yet been intensively addressed. Here, we synthesized large-area uniform WS_2xSe_2-2x alloys for room-temperature gas sensors. As-synthesized WS_2xSe_2-2x alloys exhibit an elaborative composition control owing to their thermodynamically stable sulfurization process. Further, utilizing uniform WS_2xSe_2-2x alloys over a large area, we demonstrated improved NO₂-sensing performance compared to WSe₂ on the basis of an electronic sensitization mechanism. The WS_0.96Se_1.04 alloy gas sensor exhibits 2.4 times enhanced response for NO₂ exposure. Further, we demonstrated a low-power wearable NO₂-detecting wristband that operates at room temperature. Our results show that the proposed method is a promising strategy to improve 2D TMDC gas sensors and has a potential for applications in advanced gas-sensing devices.