Gas-Sensing Performance of Ru- or Rh-Modified ZrS2 Monolayers toward Typical Lung Cancer Biomarker Gases: A DFT Study

Abstract Early detection of lung cancer via exhaled breath analysis requires gas-sensing materials with high sensitivity and selectivity. In this work, the sensing performance of Ru- and Rh-modified ZrS2 monolayers toward representative biomarkers (benzene (C6H6), acetone (C3H6O), and isoprene (C5H8)) is systematically investigated using density functional theory (DFT). The results show that transition-metal modification significantly enhances gas adsorption, converting weak physisorption on pristine ZrS2 into strong chemisorption on transition metal (TM)-decorated surfaces. Electronic structure analyses reveal pronounced orbital hybridization and charge transfer between the adsorbed molecules and TM–ZrS2 systems, leading to strong interaction and stable adsorption configurations. Selectivity evaluation indicates that Rh–ZrS2 exhibits excellent anti-interference capability against common exhaled gases, while Ru–ZrS2 shows moderate selectivity with potential interference from O2. Sensitivity analysis based on band gap modulation demonstrates that Ru–ZrS2 is highly responsive to C6H6, whereas Rh–ZrS2 shows superior sensitivity toward C3H6O and C5H8. In addition, recovery time calculations suggest that rapid desorption can be achieved under UV-assisted conditions at elevated temperatures. These results demonstrate that TM-modified ZrS2 monolayers, particularly Rh–ZrS2, are promising candidates for high–performance gas sensors, offering theoretical support for noninvasive lung cancer diagnosis.