Efficient detection of specific volatile organic compounds using functionalized titanium carbide (Ti₃C₂T_x) MXenes

Early diagnosis of cancer is crucially important for prescribing a therapy plan to possibly save human lives. Towards this end, one amongst the pathologies is to consider the efficient detection of volatile organic compounds (VOCs) related, for instance, to the pancreatic cancer existing in exhaled breath, bile, or urine of patients. The scope of the present investigation is to search for suitable materials used for detecting the specific VOCs with high sensitivity and selectivity. The density functional theory (DFT) is employed to study the adsorption of three representative pancreatic cancer biomarkers; namely, (i) 2-pentanone (2p-none), (ii) 4-ethyl-1–2-dimethylbenzene (4E1-2DMB), and (iii) N-nonanal (N-nonal) on the pristine titanium carbides MXenes (Ti₃C₂T_x, T_x = O, S, F) as well as doped with selected transition metals “TMs” (e.g., Co, Cu, Fe, Ni). At the level of pristine MXenes, a clear selective adsorption towards the three VOCs is obtained as compared to the interfering air molecules (N₂, O₂, CO₂, H₂O) with suitable adsorption energies ranging from −0.60 eV to −1.10 eV. Furthermore, the strongest adsorption of VOCs is always found to correspond to Ti₃C₂O₂ MXenes. Four different scenarios of TM-doping were considered and among which two cases are found to be effective to enhance the adsorptions of VOCs with effects on Fermi states. These latter two cases correspond to TM-doping O site and TM ad-atom. Adsorptions of VOCs on Cu-doped MXenes is found to have mimic effect on Fermi states and thus Cu should be excluded from the candidature. We concluded that TM-doping Ti₃C₂O₂ MXenes (with TM = Co, Fe, Ni) should be a good candidate material for fabrication of platform of disposable biosensor with high selectivity towards the detection of pancreatic cancer biomarkers.