DFT Investigation of Tetragonal Boron Nitride Nanoflakes for CO, NO, HCN, BrCl, F ₂ , Br ₂ , and Cl ₂ Hazardous Gas Sensing

In this study, we employed density functional theory (DFT) to investigate the stability and adsorption performance of tetragonal boron nitride (T-BN) nanoflakes toward toxic gases, including CO, NO, HCN, BrCl, F2, Br2, and Cl2. Vibrational frequency analysis confirmed the dynamical stability of T-BN. We performed comprehensive analyses, including adsorption energy, recovery time, Mulliken charge distribution, frontier molecular orbital (FMO) characteristics, partial density of states (PDOS), electrical conductivity, work function, sensitivity, quantum molecular descriptors, and thermodynamic parameters, to explore the potential gas-sensing applications of the T-BN nanoflake. The global minimum structure analysis revealed that all target gases preferentially adsorb at the octagonal site. Adsorption energy and recovery time analyses demonstrated negative adsorption energies for all gases, with Br2 and BrCl exhibiting the highest adsorption energies along with favorable recovery times, indicating the potential for sensor reusability. Furthermore, Quantum Theory of Atoms in Molecules (QTAIM) and noncovalent interaction (NCI) analyses were conducted to elucidate the nature and visualization of the interactions, confirming the presence of interactions between the nanoflake and the target gas molecules. Based on the obtained results, it can be concluded that T-BN nanoflakes hold promise as potential candidates for toxic gas-sensing applications.