First-Principles Study on Bi 2 Te 2 S Monolayer for Adsorption Performance and Sensing Capability.

In this study, a comprehensive investigation into the gas sensing capabilities of the two-dimensional (2D) Bi 2 Te 2 S was conducted using first-principles calculations based on density functional theory. A wide array of gas molecules, including CH 4 , Cl 2 , CO, CO 2 , H 2 , H 2 O, H 2 S, N 2 , NH 3 , NO, NO 2 , O 2 , and SO 2 , was encompassed in this work. Through the strategic placement of these gas molecules at different locations on the Bi 2 Te 2 S monolayer and taking into account a range of configurations, the adsorption process was thoroughly investigated, with a particular emphasis on the structures that are most thermodynamically stable. It was revealed that Cl 2 , O 2 , NO, and NO 2 molecules exhibit a pronounced affinity for the Bi 2 Te 2 S monolayer. Notably, it was found that the Cl 2 @Bi 2 Te 2 S, O 2 @Bi 2 Te 2 S, and NO 2 @Bi 2 Te 2 S systems' gas adsorption capabilities are greatly enhanced by the introduction of an external electric field. Moreover, the addition of horizontal biaxial strain significantly impacts the gas adsorption properties of the O 2 @Bi 2 Te 2 S system, underscoring the tunability of the Bi 2 Te 2 S monolayer's sensing capabilities. In light of these theoretical results, the Bi 2 Te 2 S monolayer is proposed to have great potential as an extremely sensitive and selective gas sensing material, especially for identifying Cl 2 , O 2 , NO, and NO 2 . This study clarifies the intrinsic gas sensing capabilities of the Bi 2 Te 2 S monolayer, while highlighting how its performance can be tailored in response to external stimuli, setting the stage for the advancement of more sophisticated gas sensing devices.