Ab initio investigation of functionalization of titanium carbide Ti3C2 MXenes to tune the selective detection of lung cancer biomarkers

Abstract Selected volatile organic compounds (VOCs), such as benzene (C 6 H 6 ), cyclohexane (C 6 H 12 ), isoprene (C 5 H 8 ), cyclopropanone (C 3 H 4 O), propanol (C 3 H 8 O), and butyraldehyde butanal (C 4 H 8 O), in exhaled human breath can act as indicators or biomarkers of lung cancer diseases. Detection of such VOCs with low density would pave the way for an early diagnosis of the disease and thus early treatment and cure. In the present investigation, the density-functional theory (DFT) is applied to study the detection of the mentioned VOCs on Ti 3 C 2 T X MXenes, saturated with the functional groups T x = O, F, S, and OH. For selectivity, comparative sensing of other interfering air molecules from exhaled breath, such as O 2 , N 2 , CO 2 , and H 2 O is further undertaken. Three functionalization (T x = O, F, and S) are found promising for the selective detection of the studied VOCs, in particular Ti 3 C 2 O 2 MXenes has shown distinct sensor response toward the C 5 H 8 , C 6 H 6 , C 6 H 12 , and C 3 H 4 O. The relatively strong physisorption ( $${E}_{ads}\cong -0.45 to-0.65 {\text{eV}}$$ E ads ≅ - 0.45 t o - 0.65 eV ), triggered between VOC and MXene due to an enhancement of van der Waals interaction, is found responsible to affect the near Fermi level states, which in turn controls the conductivity and consequently the sensor response. Meanwhile, such intermediate-strength interactions remain moderate to yield small desorption recovery time (of order $$\tau \cong \mu {\text{s}}-{\text{ms}})$$ τ ≅ μ s - ms ) using visible light at room temperature. Thus, Ti 3 C 2 O 2 MXenes are found promising candidate material for reusable biosensor for the early diagnosis of lung cancer diseases through the VOC detection in exhaled breath.