First-Principles Study on Bi₂Te₂S Monolayer for Adsorption Performance and Sensing Capability

In this study, a comprehensive investigation into the gas sensing capabilities of the two-dimensional (2D) Bi₂Te₂S was conducted using first-principles calculations based on density functional theory. A wide array of gas molecules, including CH₄, Cl₂, CO, CO₂, H₂, H₂O, H₂S, N₂, NH₃, NO, NO₂, O₂, and SO₂, was encompassed in this work. Through the strategic placement of these gas molecules at different locations on the Bi₂Te₂S 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 Cl₂, O₂, NO, and NO₂ molecules exhibit a pronounced affinity for the Bi₂Te₂S monolayer. Notably, it was found that the Cl₂@Bi₂Te₂S, O₂@Bi₂Te₂S, and NO₂@Bi₂Te₂S 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 O₂@Bi₂Te₂S system, underscoring the tunability of the Bi₂Te₂S monolayer's sensing capabilities. In light of these theoretical results, the Bi₂Te₂S monolayer is proposed to have great potential as an extremely sensitive and selective gas sensing material, especially for identifying Cl₂, O₂, NO, and NO₂. This study clarifies the intrinsic gas sensing capabilities of the Bi₂Te₂S 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.