First-Principles Investigation of Nitrogen-Doped Layered MoSe2 for Exhaled Volatile Organic Compound Sensing towards Early Lung Cancer Detection

Abstract Early, non-invasive lung-cancer screening based on exhaled volatile organic compounds (VOCs) has motivated the development of sensitive and selective two-dimensional gas-sensing materials. Herein, spin-polarized density functional theory calculations were employed to investigate Nitrogen-doped layered MoSe 2 (N- MoSe 2 ) as a candidate sensing material for three representative exhaled VOCs associated with lung cancer—benzene (C 6 H 6 ), acetone (C 3 H 6 O), and isoprene (C 5 H 8 ), benchmarked against pristine MoSe 2 monolayer. Nitrogen incorporation substantially enhanced the adsorption of all three VOCs, with adsorption energies changing from −0.41, −0.76, and −1.29 eV on pristine MoSe 2 to −0.61, −1.25, and −2.05 eV on N- MoSe 2 for C 6 H 6 , C 3 H 6 O, and C 5 H 8 , respectively. Hirshfeld analysis attributed this to a localized negative charge on the N dopant (−0.234 to −0.264 e) rather than large charge transfer. N-doping introduced a Fermi-level impurity state, narrowing the band gap from 1.55 to 0.57 eV, and raised sensitivity to 88.09–94.50% versus 82.46–85.54% for pristine MoSe 2 . Recovery-time analysis indicated comparatively rapid desorption of benzene/acetone but strong isoprene chemisorption, reversible via UV/thermal treatment (400–500 K). These results identify N- MoSe 2 as a promising theoretical candidate for exhaled-VOC sensing and provide a basis for subsequent experimental assessment of its suitability for breath-based lung-cancer screening.