Efficient detection of specific volatile organic compounds associated with COVID-19 using CrX₂ (X = Se, Te) monolayers

Motivated by the necessity of efficient detection of COVID-19 through specific biomarkers, such as ethyl butyrate and heptanal, we performed first principles calculations based on density functional theory (DFT) to explore the sensing mechanism of pure, vacancy-induced, and single atom catalyzed CrX₂ (X = Se, Te) monolayers. Both the biomarkers barely bind on pristine CrSe_2. However with Se-vacancy (As-doping) suitable adsorption energies of −1.44 (−0.70), and −0.70 (−0.54) eV were obtained for ethyl butyrate and heptanal, respectively. Te-vacancy (Sn-doping) in CrTe₂ resulted in much stronger binding of ethyl butyrate and heptanal with the adsorption energies of −2.04 (−2.40), and −2.90 (−2.40) eV, respectively. The adsorption of the mentioned biomarkers altered the magnetic and electronic properties of defected CrX₂, which were explored through spin-polarized density of states, electrostatic potential and work function calculations. Measurable changes in electronic and magnetic properties confirmed excellent sensing potential of CrX₂. Statistical thermodynamics analysis based on Langmuir adsorption model was employed to study the sensing of the biomarkers at different temperature and pressure ranges for real-world application.