Gas-Sensing Mechanisms of Water-Resistant Transition-Metal-Doped MoS₂ for Lung Cancer Biomarker Detection

Early-stage lung cancer screening based on breath analysis is often limited by the difficulty of reliably detecting ultralow concentrations of volatile organic compounds (VOCs) with sufficient sensitivity and selectivity. To address this issue, density functional theory (DFT) calculations are employed to examine the interaction behaviors between several VOC biomarkers (C₃H₄O, C₃H₆O, C₃H₈O, and C₅H₈) and both pristine and transition-metal-modified MoS₂ monolayers (Fe, Cu, and Co) with the aim of identifying promising material systems for efficient gas sensing at the atomic scale. A systematic evaluation encompassing structural stability, adsorption characteristics, electronic band properties, density of states, and charge transfer behavior reveals how dopant incorporation governs both the electronic configuration of the material and its gas-sensing response. The results show that pristine MoS₂ interacts weakly with target molecules and exhibits a negligible electrical response, whereas transition-metal doping effectively reconstructs the local electronic environment, significantly enhancing adsorption strength and electronic modulation. Among the studied systems, Co-doped MoS₂ achieves an optimal balance between adsorption strength and desorption capability, leading to superior overall sensing performance. Band structure and density-of-state analyses reveal that gas adsorption induces a pronounced electronic state redistribution near the Fermi level, which is critical for achieving high sensitivity. Furthermore, in the presence of background interference such as H₂O, the doped systems can rapidly recover their structural integrity and electronic stability after water removal, demonstrating a strong anti-interference capability and environmental adaptability. This feature effectively suppresses the influence of nontarget species in complex breath environments and significantly improves the sensing reliability and reproducibility. From an application perspective, these findings provide valuable guidance for the design of high-performance gas sensors, offering key support for high-precision detection under complex conditions and representing an important step toward improving sensing accuracy and practical applicability.