Atomistic Insights into Detection of Volatile Organic Compounds Using Transition Metal Dichalcogenides-Based Nanosensors

Detecting volatile organic compounds (VOCs) linked to colorectal cancer, like benzaldehyde, indole, and propan-2-ol, could provide a promising approach for early diagnosis. This study deals with the sensing properties of tungsten diselenide (WSe₂) and tungsten ditelluride (WTe₂) monolayers toward specific VOCs. First-principles density functional theory (DFT) calculations reveal relatively weak adsorption energies (<i>E</i>_ads) of -0.67 (-0.85), -0.81 (-0.991), and -0.42 (-0.60) for benzaldehyde, indole, and propan-2-ol, respectively, on pristine WSe₂ (WTe₂). For efficient sensing, the adsorption mechanism is enhanced by incorporating selected single atoms, such as Fe, Mn, and Zn, into the WSe₂ and WTe₂. We find Fe-WSe₂ has improved the <i>E</i>_ads values to -1.10, -1.56, and -1.26 eV for benzaldehyde, indole, and propan-2-ol, respectively, which are ideal for practical sensing applications. Considerable changes in the electronic properties further support its effectiveness as an efficient nanosensing material. We further explore the charge transfer mechanism, electrostatic potential, and work function to authenticate the VOC sensing behaviors of the studied systems. Lastly, the Langmuir adsorption model shows that Fe-WSe₂ and Mn-WSe₂ have the potential to quantitatively detect benzaldehyde and propan-2-ol at concentrations below ppm and ppb levels, respectively, whereas indole can be detected at below ppt levels. We believe that these findings will contribute to the development of highly sensitive nanosensors for the early detection of colorectal cancer-related VOCs, thereby enhancing diagnosis and facilitating early interventions that can significantly improve survival rates.