A theoretical study on the electronic sensitivity of the pristine and Al-doped B24N24 nanoclusters to F2CO and Cl2CO gases

The adsorption behavior and electronic sensitivity of the pristine, and Al-doped B24N24 (Al-BN) nanoclusters toward two carbonyl halides (F2CO, and Cl2CO (phosgene)) were investigated using density functional calculations. It was found that the carbonyl halides interact with the pristine cluster very weakly while by replacing a B atom of the cluster with an Al atom, the adsorption energy is significantly increased. The electronic properties of the pristine BN nanocluster are not sensitive to F2CO but after the Cl2CO adsorption, its HOMO-LUMO gap (E (g)) is significantly decreased. Despite this decrease, the BN cage is still insulator and cannot be used as a sensor. The Al-doping overcomes this problem by a primarily reduction in the E (g) (from 6.45 to 4.88 eV). Our calculations indicate that by F2CO and Cl2CO adsorptions, the Al-BN cluster is transformed from insulator to a semiconductor. This phenomenon largely increases the electrical conductivity of Al-BN and can produce electrical noise which is responsible for the gas detection. Also, it is shown that the Al-BN selectively responses to F2CO and Cl2CO gases.