Determination of toxic carbonyl species including acetone, formaldehyde, and phosgene by polyaniline emeraldine gas sensor using DFT calculation

Abstract

Detection of toxic carbonyl gases such as acetone, formaldehyde, and phosgene by polyaniline emeraldine salt (PANI ES) was theoretically investigated using the UB3LYP/6-31G(d) level of theory. Sensing potentials of nPANI ES (n=2, 4, 6, and 8) complexed with toxic carbonyl gases were described in terms of structural, electronic, and optical properties. We found that HOMO-LUMO gaps of PANI ES after response to toxic carbonyl compounds are decreased, revealing higher electron delocalization and conductivity along backbone of PANI ES complexes compared with bare PANI ES. Phosgene shows the highest conductivity followed by formaldehyde and acetone, respectively, while reverse tendency was detected for interaction energies. UV–vis-NIR spectra estimated by means of TD-UB3LYP/6-31G(d) method of PANI ES complexes are all blue-shifted compared to their intrinsic structures, confirming the n-type doping process. The amount of blue-shift for acetone sensing is distinctly higher than those observed for formaldehyde and phosgene. These obtained results not only revealed a conductivity enhancement of polyaniline emeraldine salt sensing with toxic carbonyl gases but also demonstrated an ability to determine such toxic gases by utilizing optical measurement.