Adsorption and gas-sensing performance of a ZnO-decorated WSe₂ monolayer for toxic gas detection: a first-principles...

The reliable detection of toxic and greenhouse gases is essential for environmental monitoring, industrial safety, and public health protection. In this work, a comprehensive first-principles density functional theory study was carried out to investigate the adsorption and gas-sensing performance of a ZnO-decorated WSe₂ monolayer toward CO₂, N₂O, CH₄, SF₆, CCl₂O and CH₃Cl gases. The results show that pristine WSe₂ exhibits weak adsorption due to limited gas-surface interaction, whereas ZnO decoration significantly enhances the adsorption behavior by increasing adsorption energies, reducing adsorption distances, and promoting charge transfer. Among the investigated gases, the ZnO-WSe₂ system exhibits the strongest interaction toward CCl₂O and CH₄, with adsorption energies of -0.566 eV and -0.542 eV, respectively. Electronic structure analysis, including band structure, density of states, differential charge density, and work function calculations, reveals pronounced gas-dependent electronic responses and confirms strong modulation of the electronic properties after gas adsorption. Sensitivity analysis indicates that the ZnO-WSe₂ monolayer exhibits excellent sensing performance, particularly toward CCl₂O, with appreciable responses also observed for CO₂ and CH₄, while recovery time calculations demonstrate that the desorption behavior can be effectively tuned by temperature. Furthermore, the strong binding interaction between ZnO and WSe₂ confirms the structural stability of the decorated monolayer under practical sensing conditions. These findings demonstrate that ZnO decoration is an effective strategy for activating the WSe₂ surface and improving its gas-sensing performance, highlighting ZnO-WSe₂ as a promising and selective sensing material for toxic gas detection and providing valuable theoretical guidance for the design of high-performance two-dimensional gas sensors.