Molecular dynamics simulation and quantum chemical studies on the investigation of aluminum nitride nanotube as phosgene gas sensor

The present work utilizes density functional theory (DFT) and molecular dynamics (MD) calculations to investigate the adsorption process of phosgene (COCl2) molecule on the pristine aluminum nitride nanotube (AlNNT). Quantum chemical calculations by DFT provide detailed geometrical parameters, electronic properties and the adsorption energies for the AlNNT and five different COCl2 configurations on the nanotube. DFT calculations confirmed the energetic stability of the optimized geometries and revealed that COCl2 molecule adsorbed on the pristine AlNNT through weak van der Waals (vdW) interaction, which means that the adsorption is physisorption process. The results of the theoretical investigations show that the adsorption of the COCl2 molecule on the nanotube surface results in a decrease the energy gap (Eg). Thus, the reactivity and electrical conductivity increase upon the adsorption process. Moreover, the reliable assessment of the dynamic adsorption of various air pollutant gas molecules i.e., carbon dioxide (CO2), carbon monoxide (CO), nitrous oxide (N2O), nitrogen dioxide (NO2) and phosgene on the nanotube surface is examined by complementing traditional analysis of MD simulations, such as the time-evolution of the root mean square deviation (RMSD), radial distribution functions (RDF), the number of gas molecules and number of contacts, along with the energetics profiles. Furthermore, close inspection of the results of RDF patterns and the van der Waals energy calculations implies the remarkable interaction between phosgene molecule and nanotube surface. According to the molecular dynamics simulation study, it can be concluded that AlNNT can be a promising candidate in gas sensor devices for detecting the COCl2 molecule.