Detection of Lung Cancer Biomarkers C ₃ H ₆ O, CH ₂ O, and C ₅ H ₈ through Pd-, Pt-, and Ag-Doped BC ₆ N Monolayers: A Density Functional Theory Study

Early detection of lung cancer remains a major clinical challenge, limited by the high cost, invasiveness, and insufficient sensitivity of current diagnostic methods. Exhaled volatile organic compounds (VOCs), such as acetone (C₃H₆O), formaldehyde (CH₂O), and isoprene (C₅H₈), have emerged as promising noninvasive biomarkers, with elevated concentrations observed in the breath of lung cancer patients. In this study, we employ density functional theory (DFT) to evaluate the sensing performance of pristine and transition-metal (TM)-doped (Pd, Pt, and Ag) BC₆N monolayers toward these VOCs. TM doping was found to significantly enhance adsorption strength and sensing response compared to the pristine surface, with Pd-, Pt-, and Ag-doped BC₆N exhibiting notably greater adsorption energies (-0.295 to -2.211 eV) than the pure monolayer (0.001 to -0.086 eV). Among the dopants, Ag-BC₆N displays the most favorable sensing properties, including moderate adsorption energies (-0.295 to -0.535 eV), short adsorption distances (2.23-2.31 Å), and rapid recovery times (9.74 × 10^-4 to 9.84 × 10^-8 s), indicating superior reversibility relative to Pd and Pt. Band structure, charge transfer, and projected density of states (PDOS) analyses further reveal strong orbital hybridization and electronic modulation upon VOC adsorption. These findings establish Ag-BC₆N, in particular, as a highly promising sensor for sensitive, scalable, and reusable detection of lung cancer biomarkers via breath analysis.