Smart Sensing Characteristicsof Tungsten Diselenide(WSe₂) Monolayers toward Depression-Related Volatile OrganicCompounds

In this study, we designed efficient nanobiosensors based on two-dimensional tungsten diselenide (WSe₂) monolayers to detect specific volatile organic compounds (VOCs) related to depression, such as butyric acid, furan, <i>N</i>-butylamine, and trimethylamine. First-principles calculations based on density functional theory revealed weak adsorption energies (<i>E</i>_ads) on pristine (WSe₂) and single Se-vacancy-induced (V_Se–WSe₂) monolayers. However, doping single atoms of Co, Fe, and Ni in WSe₂ at small concentrations of 1.33% not only improved the <i>E</i>_ads values but also altered the electronic structures, which are essential for efficient sensing applications. Among the doped systems, Fe@WSe₂ showed tremendous improvement in its adsorption mechanism. Bader charge analysis, electrostatic potential, and work function calculations further validated the VOC sensing capabilities of the single-atom-dispersed WSe₂ monolayers. Additionally, the detection of VOCs under varying temperature and pressure conditions was investigated by using statistical thermodynamic analysis based on the Langmuir adsorption model.