First-principles investigation of Si-functionalized monolayer WSe₂ for the detection of lung cancer VOCs

Lung cancer (LC) is still among the most fatal cancers, in large part because of the difficulty of early detection. The present work explores a silicon-functionalized tungsten diselenide monolayer (Si-WSe₂) as a potential biosensing platform for non-invasive VOC detection with LC biomarkers. Using density functional theory (DFT) in generalized gradient approximation (GGA), we critically examine the impact of silicon doping on the electronic characteristics of WSe₂. Parameters such as binding energy, adsorption energy, charge transfer, density of states (DOS), and sensitivity are computed for C₃H₄O, C₅H₈, and C₃H₈O. Our results show that Si-doping not only lowers the bandgap significantly (from 1.5 eV to 0.53 eV) but also enhances adsorption properties, with C₅H₈ and C₃H₄O displaying strong chemisorption (adsorption energies of −1.97 eV and −1.80 eV, respectively) compared to physisorption C₃H₈O (-0.80 eV). The DOS and projected DOS (PDOS) variations corroborate extensive charge redistribution and orbital hybridization at the Fermi level, in agreement with the observed high sensitivity, particularly for C₃H₄O (99.95 %). These results substantiate the viability of Si-WSe₂ in the construction of rapid, sensitive, and selective breath-based diagnostic devices for the early diagnosis of LC.