Sensing of Lung Cancer Biomarkers Using Titanium Carbide (Ti2C) MXenes

Abstract

Recent studies have shown that titanium carbide MXenes are promising 2D materials for sensing volatile organic compounds (VOCs) in human breath. While pristine titanium carbide MXenes exhibit, in general metallic characteristics, functionalization modifies their electronic properties. In this study, Ti₂C monolayer functionalized with oxygen (O), hydroxyl group (OH), sulfur (S), and fluorine (F) are investigated for their sensing characteristic for various VOCs namely aniline (C₆H₇N), ethylbenzene (C₈H₁₀), 4-methyloctane (C₉H₂₀), and undecane (C₁₁H₂₄). The results based on van der Waals density functional theory find that the VOCs undergo chemisorption over these functionalized monolayers. This is affirmed by calculation of electrostatic potential and Bader charge analysis. Aniline acts as an electron donor primarily attributed to the electron-donating nature of its nitrogen atom, whereas other molecules act as electron acceptors in the adsorbed complexes. The calculation of conductance and current-voltage (I-V) characteristics show the high sensitivity of aniline when interacting with the OH-functionalized Ti2C monolayer, compared to other VOC-monolayer complexes. This may be due to the low work function of OH-functionalized monolayer together with the donor nature of aniline. The insights gained from this study are expected to contribute to the future development of biomarkers with targeted VOCs selectivity through the appropriate functionalization of MXenes.