Electric field effects on CO2 adsorption and electronic transport in MoS2: toward FET-based gas sensors

Two-dimensional (2D) materials are promising candidates for gas sensing, but achieving selective CO₂ sensing remains challenging. Here, we combine density functional theory and nonequilibrium Green's function calculations to study how varying electric field strength modulates adsorption on the surface and quantum transport within monolayer MoS₂. Among the six gases investigated (CO, CO₂, CH₄, O₂, N₂, and H₂O), only CO₂ exhibits a transition from physisorption to chemisorption under the applied field, resulting in stronger binding. In contrast, N₂ and O₂ desorb, enabling selective CO₂ adsorption. At higher CO₂ coverages, the electric field enhances adsorption stability but cannot completely prevent saturation. We further explore CO₂ detection using MoS₂ FETs under gate-induced fields. The current sensitivity rises from 1.7 % for one adsorbed molecule to 64.3 % for five, while recovery time decreases. These results clarify the role of electric fields in tuning surface adsorption and charge transport in 2D semiconductors, supporting the design of FET-based gas sensors