Engineering AlN nanoclusters via Mg and Si doping for enhanced chlorofluorocarbon sensing: A combined DFT, TD-DFT, and QTAIM study

Chlorofluorocarbons (CFCs), such as CHF₂Cl, are extensively utilized as refrigerants and intermediates in cooling systems; however, their emission contributes significantly to stratospheric ozone depletion. Therefore, the development of efficient and selective sensing materials for CFC detection is of paramount importance. In this work, pristine, Mg- and Si-doped aluminum nitride (AlN) nanoclusters were systematically modeled and examined to evaluate their potential as CHF₂Cl sensors using density functional theory (DFT) calculations at the B۳LYP/۶-۳۱g* level. The results reveal that Mg-doped nanoclusters, particularly Al₆MgN₅, exhibit the most promising sensing behavior toward CHF₂Cl, characterized by enhanced adsorption energies (up to –۱۱.۴۴ kcal mol⁻¹), substantial HOMO–LUMO gap modulation (ΔEg ≈ ۲۵%), and a pronounced UV–Vis optical response (λmax = ۱۱۶۳.۹۹ nm). These characteristics indicate a significant enhancement in sensing performance. In contrast, pristine and Si-doped nanoclusters display weaker interactions and limited conductivity modulation, making them less suitable for sensing applications. The alignment of frontier orbitals indicates that electron transfer is dominated by F–Mg interactions, which not only stabilize the complex but also underpin the improved electronic response. The nature of bond critical points between CHF₂Cl and the Al₆MgN₅ nanocluster was further examined using the quantum theory of atoms in molecules (QTAIM), indicating the typical of closed-shell interactions with predominantly electrostatic origin, confirming the physical nature of the hydrogen bonding. Importantly, such physically driven interactions are highly advantageous for sensing applications, as they provide sufficient adsorption strength for analyte recognition while maintaining reversibility. Further exploration of interaction characteristics through MEP and TD-DFT analyses demonstrated charge redistribution and adsorption-induced electronic transition variations. These findings suggest that Mg-doped AlN nanoclusters are promising candidates for CFC sensing applications and providing a theoretical foundation for rational sensor design in environmental monitoring applications, although further studies involving competing gases are required to fully evaluate selectivity.

کلیدواژه ها:

Chlorofluorocarbons ، AlN nanoclusters ، Mg/Si doping ، Gas Sensor ، TD-DFT ، QTAIM