In the present study, the adsorption of aniline over the surface of all-boron B40 was examined through density functional theory. Moreover, to judge the impact of Mn and Fe transition metal atoms on the adsorption behavior of aniline, we scrutinized the modulation process of B40, which includes substitutional doping and encapsulation with a single Mn and Fe atom. For further investigations, in addition to the gas phase, all calculations were performed by considering water as the solvent. In both phases, the calculation results demonstrate that aniline molecule strongly interacts with the B40 via its nitrogen head. On the other hand, based on the calculated data, the presence of Mn and Fe atoms can change the chemical reactivity of pristine nanocage. The comparison of the modification approaches reveals that Mn and Fe doping of the B40 leads to the noticeable improvement in the adsorption strength. However, assessment of the results in both phases identifies the slight difference between the values of adsorption energy in the gas phase and aqueous solution. Therefore, based on the adsorption energies, the adsorption strength decreases in the sequence M-doped B40 > M-encapsulated B40 > B40, which M is Mn and Fe atoms. Consequently, as the highest ability for the adsorption of aniline has been obtained for M-doped cages, we conclude that doping B40 with Mn and Fe atoms can be an efficient approach for the removal of aniline.
