Theoretical investigation of Al-doped biphenylene as efficient sensor for phosgene detection

Phosgene (COCl₂) is a highly toxic gas that poses significant risks to human health and the environment, making its detection and monitoring critically important. In this study, we explored the potential of pristine and aluminum-doped biphenylene (BP) monolayers as sensing materials for phosgene detection using the M062X/6-31G(d,p) level of theory. Aluminum doping was shown to disrupt the uniform electronic density of BP, creating active sites that significantly enhance its reactivity. While phosgene adsorption on pristine BP was weak, with an adsorption energy of −6.93 kcal/mol and minimal changes in electronic properties, thermochemical analysis confirmed that this interaction is non-spontaneous under standard conditions. In contrast, Al-doped BP monolayers (Al1-BP and Al2-BP) exhibited strong phosgene adsorption, with adsorption energies of −20.09 kcal/mol and −21.47 kcal/mol, respectively. Notably, a significant change in the energy gap was observed upon phosgene adsorption on the doped monolayers, and the process was found to be thermodynamically favorable, as indicated by negative free energy values. Natural bond orbital (NBO) analysis revealed that the enhanced sensitivity and reactivity of Al-doped BP arise from donor-acceptor interactions between the lone pair electrons of phosgene oxygen and the Rydberg state of lone pairs from the aluminum dopant. These results demonstrate the promising potential of Al-doped BP monolayers as highly sensitive and efficient materials for phosgene detection.