Picric Acid Adsorption on the Surface of Pristine and Al-doped Boron Nitride Nanocluster: a Comprehensive Theoretical Study

In this research, the performance of pristine and Al-doped boron nitride nanocage as a sensing material and adsorbent for the detection and removal of picric acid was investigated by infra-red (IR), frontier molecular orbital (FMO), and natural orbital bond (NBO) computations. The calculated negative adsorption energies showed that picric acid interactions with both pristine and Al-doped adsorbents were experimentally feasible. The NBO results indicated that picric acid interactions with B12N12 and AlB11N12 were chemisorption and physisorption, respectively. The negative values of adsorption enthalpy changes and Gibbs free energy changes demonstrated that picric acid interaction with both adsorbents was exothermic and spontaneously. The values of thermodynamic equilibrium constants (Kth) revealed that picric acid adsorption on the surface of pristine and Al-doped adsorbents was irreversible and reversible, respectively. The increase in the specific heat capacity (CV) of both nanostructures in the adsorption process showed that both adsorbents could be used as a sensing material for the construction of new thermal sensors for picric acid detection. In the adsorption process, the bandgap of B12N12 declined by 38.811%: from 14.970 to 9.160 eV; but the bandgap of AlB11N12 decreased by 72.495%: from 12.520 to 3.444 eV. Hence, the Al-doped boron nitride cage was a better sensing material for the development of novel electrochemical sensors for the determination of picric acid. The results of temperature and solvent effects on the interaction process showed that the adsorption process was more favorable at lower temperatures and the presence of water had no significant effects on the interactions.