Remarkable enhancement in sensor ability of polyaniline upon composite formation with ZnO for industrial effluents.

Polyaniline emeraldine salt and Polyaniline Zinc Oxide composite are comprehensively studied to compare their sensing ability towards ammonia, acetone, methanol and ethanol. Sensing ability is evaluated through thermodynamic, geometric and electronic parameters. A number of orientations are evaluated in search for the lowest energy structure. The comparison of thermodynamic, geometric and electronic parameters of simple and composite sensors confirmed that composite sensor shows better sensing ability than simple PANI. Composite formation between polyaniline and zinc oxide is a thermodynamically feasible process with interaction energy of -42.8 kcal/mol. Both sensor shows highest interaction energy for ethanol among four analytes. Composite sensor shows almost twice the interaction with ethanol, methanol and acetone while 1.5 times the interaction energy for ammonia. The results of run simulations and subsequent calculations showed that in composite sensors, zinc oxide not only enhances the binding power of conducting polymer with analytes but also interacts directly with analytes. Strong hydrogen bonding as well as weak dispersion forces of attraction are responsible for the stability of composite and all complexes, as revealed by non-covalent interaction (NCI) studies. Acetone shows a different behaviour in composite sensor complex than other analytes.